How to Buy a Pulse Oximeter: CPAP, Nebulizer & O2 Concentrator Guide 2026

Quick Answer: Which Respiratory Device Do You Need — and Do You Need a Prescription?

A pulse oximeter requires no prescription in the United States and costs $25–$60 for a 510(k)-cleared model suitable for home monitoring. CPAP, BiPAP, and APAP machines, along with oxygen concentrators, are FDA Class II devices that require a physician prescription and are covered by Medicare Part B with qualifying documentation. Nebulizer devices are sold over the counter, though the medications used in them require a prescription.

Jump to: Which device do I need? · Buying a pulse oximeter · Buying a CPAP · Choosing a nebulizer · Buying an oxygen concentrator · FAQ

⚠️ When to Consult a Healthcare Provider

This page is reviewed by a licensed physician and updated to reflect current FDA guidance and Medicare coverage criteria. It is educational and does not constitute medical advice. CPAP machines and oxygen concentrators require a prescription issued by a licensed clinician. If you are uncertain which device category applies to your situation, consult your physician, pulmonologist, or sleep specialist before purchasing.

See our medical oversight standards for the governance framework that applies to this content.

Who This Guide Is For

Whether you’re a patient newly diagnosed with sleep apnea or COPD, a caregiver helping a parent or partner manage a respiratory condition, or a general health enthusiast researching pulse oximeters — this guide walks you through every device category in plain English. All devices covered are available in the United States.

Navigating respiratory devices can feel overwhelming — especially if you’ve just received a diagnosis or are helping a loved one. You might be unsure whether you need a prescription, worried about cost, or just trying to figure out which device actually applies to your situation. You’re not alone, and this guide cuts through the confusion. Use the decision trees below as a starting point — not a clinical verdict.

At a Glance: Which Device Do You Need?

All cost ranges are approximate USD out-of-pocket estimates. Insurance coverage varies by plan and diagnosis. See each device section for full coverage details.

For Sleep Apnea: CPAP, BiPAP, and APAP

Key considerations for sleep apnea device selection:

• CPAP therapy is considered a first-line treatment for moderate-to-severe obstructive sleep apnea (OSA) [American Academy of Sleep Medicine, 2023]
• A valid prescription is legally required in most jurisdictions to purchase a CPAP machine
• Auto-adjusting CPAP (APAP) may be appropriate for patients with varying pressure needs — confirm with your physician
• Pulse oximetry monitoring is sometimes used as a supplementary tool to track nocturnal oxygen desaturation, but does not diagnose OSA [U.S. Food and Drug Administration, 2022]

For COPD: Pulse Oximeters and Oxygen Concentrators

What is Long-Term Oxygen Therapy (LTOT)?
Long-term oxygen therapy is the prescribed, ongoing use of supplemental oxygen — typically for 15 or more hours per day — for patients with chronic, severe resting hypoxemia, most often from COPD. Two landmark clinical trials (the Nocturnal Oxygen Therapy Trial and the British Medical Research Council study, both from the early 1980s) established that LTOT can reduce mortality in this patient group, which is why it remains a guideline-supported intervention today.

Evidence note: Evidence suggests that long-term oxygen therapy (LTOT) may reduce mortality in COPD patients with resting hypoxemia [Nocturnal Oxygen Therapy Trial Group, 1980; MRC Working Party, 1981]. Initiation of LTOT is guided by physician assessment of arterial blood gas values and clinical history — not solely by pulse oximeter readings.

For Asthma: Pulse Oximeters and Nebulizers

Note: Pulse oximeters measure oxygen saturation (SpO₂) but do not measure airflow obstruction, peak flow, or spirometry values. They are supplementary tools in asthma management, not primary monitoring instruments [Global Initiative for Asthma (GINA), 2023].

For General Health and Fitness Tracking

What Does 510(k) Clearance Mean for a Pulse Oximeter?

A 510(k)-cleared pulse oximeter is a device the FDA has determined to be substantially equivalent to a legally marketed predicate device in safety and effectiveness, validated to measure blood oxygen saturation (SpO₂) within approximately ±2–3% RMSD of arterial blood gas measurements.

A 510(k)-cleared pulse oximeter is a device the FDA has determined to be substantially equivalent to a legally marketed predicate device in safety and effectiveness. For pulse oximeters specifically, 510(k) clearance indicates the device has been validated to measure blood oxygen saturation (SpO₂) within approximately ±2–3% RMSD of arterial blood gas measurements. The clearance number is searchable on the FDA 510(k) database.

FDA 510(k) Clearance and Accuracy: What to Verify Before Buying

Understanding regulatory status is a foundational step in pulse oximeter selection. The FDA distinguishes between three categories:

Critical accuracy considerations:

• The FDA issued a Safety Communication in 2021 and a subsequent 2024 proposed rule noting that pulse oximeter accuracy may be affected by skin pigmentation, poor perfusion, nail polish, and motion artifact.
• Clinically meaningful SpO₂ readings require devices validated on subjects with varied skin tones — check the manufacturer’s clinical validation documentation.
• An accuracy tolerance within ±2% RMSD of arterial blood gas measurements is generally accepted for clinical use (ISO 80601-2-61:2017). See how we evaluate device accuracy when assessing the devices reviewed on this site.
• Do not rely on consumer-grade devices for clinical decision-making without physician guidance.

What to verify before purchasing:

• [ ] 510(k) clearance number (searchable on the FDA database)
• [ ] Clinical validation studies available from the manufacturer
• [ ] Accuracy data across diverse skin tones
• [ ] Intended use statement on labeling

Pulse Oximeter Accuracy and Dark Skin: What the FDA’s 2024 Guidance Requires

Some pulse oximeters have shown reduced accuracy in people with darker skin pigmentation, because the device’s light-based sensor can be affected by melanin density. The FDA’s 2024 proposed rule responds to this by requiring manufacturers to validate device accuracy on subjects representing at least two darker skin tones, using the Monk Skin Tone (MST) Scale — a 10-point scale developed to represent a fuller range of human skin tones than earlier classification systems. When buying a pulse oximeter for clinical or physician-ordered monitoring, ask the manufacturer or check product documentation for multi-skin-tone validation data before purchasing.

Pulse Oximeter vs Smartwatch SpO2: Which Is Clinically Accurate?

Smartwatch and wearable SpO₂ sensors use photoplethysmography and are generally not FDA-cleared for clinical accuracy; they are designed for wellness trend monitoring, not medical decision-making.

Smartwatch and wearable SpO₂ sensors use photoplethysmography (PPG) and are generally not FDA-cleared for clinical accuracy; they are designed for wellness trend monitoring, not for medical decision-making.

For physician-ordered SpO₂ monitoring — including COPD management, post-surgical recovery, or nocturnal desaturation tracking — a 510(k)-cleared fingertip pulse oximeter is the appropriate device. If a clinician has asked you to track SpO₂ for a documented condition, a smartwatch reading should not be substituted for a clinical-grade device without your physician’s sign-off.

Display Quality: Plethysmograph, Waveform & Readability

Battery Life and Durability

Pulse Oximeter Price Tiers: Budget to Clinical-Grade

⚠️ Price is not a reliable indicator of accuracy. Always verify 510(k) clearance status independently of price tier.

Does Medicare or Insurance Cover a Pulse Oximeter?

Medicare does not cover pulse oximeters purchased over the counter for routine personal monitoring. If a physician orders a pulse oximeter as part of a documented home monitoring program — for example, following a COPD or heart-failure hospitalization — Medicare or private insurance may cover it as durable medical equipment (DME) under Part B, subject to a qualifying diagnosis and a written order. Contact your plan administrator and request a physician order if insurance coverage is a priority.

Our Recommendation: Best Pulse Oximeter for Home Monitoring

Look for an FDA 510(k)-cleared fingertip pulse oximeter validated across diverse skin tones, with a clear digital display, plethysmograph waveform, and a minimum of 510(k) clearance documentation you can verify on the FDA database. Under $60 for most home monitoring needs. → See our physician-reviewed pulse oximeter picks for 2026, ranked by 510(k) status and skin-tone validation

How to Get a CPAP Prescription: Step-by-Step

Step-by-step overview of the CPAP prescription process:

CPAP vs BiPAP vs APAP: Which Machine Type Is Right for You?

CPAP delivers a single, fixed pressure throughout the night; APAP automatically varies pressure within a physician-prescribed range based on your breathing; BiPAP delivers separate, higher pressure on inhalation and lower pressure on exhalation. A prescribing physician determines which type is appropriate.

CPAP (Continuous Positive Airway Pressure) delivers a single, fixed pressure throughout the night.

APAP (Auto-Adjusting PAP) automatically varies pressure within a physician-prescribed range based on your breathing.

BiPAP (Bilevel PAP) delivers a separate, higher pressure during inhalation (IPAP) and a lower pressure during exhalation (EPAP), and is often used for complex sleep apnea, COPD, or patients who cannot tolerate standard CPAP pressure.

Your prescribing physician determines which type is appropriate based on your sleep study results and clinical history — this is not a choice made independently by the patient.

Buying a CPAP on Behalf of a Parent or Partner

If you’re helping a loved one navigate their CPAP prescription, bring the following to their DME appointment: a copy of the sleep study results, the written prescription with prescribed pressure settings, and your insurance card. Ask the DME supplier specifically about the mask exchange program — most offer at least one swap if the first mask doesn’t fit comfortably.

CPAP Machine Features: What Matters Clinically

CPAP Mask Types and Fitting Guide

Mask selection significantly affects CPAP therapy adherence. The right mask depends on breathing pattern, facial anatomy, and personal preference.

Fitting checklist:

• [ ] Mask fits without gaps at seal points
• [ ] No pressure marks or skin irritation after a 15-minute trial
• [ ] Headgear adjusted to recommended tension (snug, not tight)
• [ ] Compatible with prescribed machine interface (check connector size)
• [ ] Size confirmed via manufacturer sizing guide or DME fitting session

Humidification Options

Note: Evidence suggests that heated humidification may improve CPAP adherence in patients experiencing upper airway dryness [Mador et al., 2005]. Humidifier use is typically individualized based on patient comfort.

CPAP Data Tracking, Compliance, and the 4-Hour Rule

Modern CPAP machines collect therapy data that may be used by clinicians to assess compliance and efficacy.

Insurance documentation note: Many payers require documented CPAP compliance — typically ≥4 hours/night on ≥70% of nights in a consecutive 30-day period — to authorize continued equipment coverage [CMS Coverage Policy, 2023]. Confirm requirements with your insurer.

CPAP compliance and the 4-hour/70% rule: Medicare and most private insurers require documented proof that you’re actually using your CPAP machine before they’ll continue covering it. The standard threshold is at least 4 hours of use per night on 70% or more of nights during a consecutive 30-day period, tracked automatically by the device’s internal data. If you fall short of this threshold during the initial compliance window, your insurer may deny continued rental payments and you could be responsible for the remaining device cost. If you’re struggling to tolerate the mask for a full night, talk to your DME supplier or sleep specialist before the compliance window closes — mask refitting often resolves the issue.

Does Medicare Cover a CPAP Machine? Insurance Explained

One of the biggest frustrations CPAP patients face is being surprised by out-of-pocket costs after assuming insurance would cover everything. Here’s how coverage actually works — and how to make sure you qualify. With the right documentation, Medicare Part B may cover up to 80% of your CPAP cost after the deductible. Private insurance plans vary, but most cover CPAP as durable medical equipment (DME) when you meet qualifying criteria

Common insurance documentation requirements:

• [ ] Written prescription specifying device type and pressure settings
• [ ] Qualifying sleep study results (AHI ≥ 5 typically; varies by payer)
• [ ] Letter of medical necessity (LMN) from prescribing physician
• [ ] Compliance data reports (after initial rental period)

Is It Safe to Buy a Used CPAP Machine?

Buying a used CPAP machine from a private seller is not recommended: the device retains the previous owner’s pressure settings, internal components may harbor pathogens that cannot be fully sanitized by the end user, the manufacturer warranty is voided, and insurance will not reimburse the purchase.

Buying a used CPAP machine from a private seller is not recommended. The device retains the previous owner’s prescribed pressure settings, which may be inappropriate or even harmful for your own airway needs. Internal components — including the air pathway and humidifier chamber — may harbor pathogens that cannot be fully sanitized by an end user.

A used machine also voids the manufacturer’s warranty and will not be reimbursed by insurance, since claims require a new device purchased through a verified DME supplier. If cost is a concern, ask your DME supplier about refurbished-but-certified units sold directly through accredited channels, which are sanitized and warrantied — unlike private peer-to-peer resale.

Our Recommendation: First CPAP Purchase

For most newly diagnosed patients, your physician and DME supplier will guide the machine selection — the prescription determines your pressure settings, and the DME will fit your mask.

Your job is to come prepared: know your AHI severity, ask about APAP if you want pressure flexibility, and always request a mask fitting session before accepting the first option. → See our reviewed CPAP machine recommendations for 2026

Nebulizer Type Comparison: Mesh vs Jet vs Ultrasonic

Medication Compatibility by Nebulizer Type

Not all nebulizers are compatible with all inhaled medications. Confirm compatibility before purchase.

⚠️ Always confirm medication compatibility with the nebulizer manufacturer and your prescribing clinician before use. Some medications can damage mesh membranes or lose efficacy when exposed to ultrasonic vibration.

Key questions to ask your pharmacist or physician:

• [ ] Is this specific medication approved for use with my nebulizer model?
• [ ] Does the medication require a specific particle size (MMAD) for optimal lung deposition?
• [ ] Should the nebulizer cup be kept at room temperature or refrigerated?

Portable vs Home Nebulizer: Which Do You Need?

Portability feature checklist:

• [ ] Battery-operated or USB-rechargeable option
• [ ] Weight and dimensions suitable for travel bag or carry-on
• [ ] Treatment time compatible with mobile use
• [ ] Carrying case or protective pouch included
• [ ] FAA / airline approval for in-flight use (for air travel needs)

Treatment Time and Long-Term Adherence

Treatment time is a meaningful factor in long-term adherence, particularly for patients requiring multiple daily treatments.

Nebulizer Insurance Coverage

Nebulizer devices are generally covered by Medicare Part B and most private insurance plans as durable medical equipment (DME) when prescribed by a physician for a qualifying condition such as asthma, COPD, or cystic fibrosis.

The device itself is typically covered; inhaled medications require a separate prescription and pharmacy benefit. To qualify: obtain a written prescription specifying the device type and diagnosis, use an in-network DME supplier, and confirm your plan’s DME coverage tier.

Replacement parts (medication cups, mouthpieces, tubing, filters) are also covered on a schedule by most plans — ask your DME supplier for the resupply timeline

Our Recommendation: Best Nebulizer by Use Case

For home-only use: a tabletop jet (compressor) nebulizer is the most cost-effective choice — durable, compatible with most medications, and typically covered by insurance.

For travel or daily on-the-go use: a portable mesh nebulizer offers quiet, fast treatment with USB charging.

Always confirm medication compatibility with your physician before purchasing a mesh model. → See our reviewed nebulizer recommendations

What SpO2 Level Qualifies You for Oxygen Therapy?

To qualify for Medicare-covered home oxygen therapy under CMS Local Coverage Determination L33797, your resting SpO₂ must be documented at or below 88% on room air, or at or below 89% during exertion or sleep.

To qualify for Medicare-covered home oxygen therapy under CMS Local Coverage Determination L33797, your resting blood oxygen level must be documented at or below 88% (SpO₂ ≤ 88%) on room air. Some patients qualify at ≤89% if the desaturation occurs specifically during exertion or sleep. These values must be confirmed by a licensed physician via arterial blood gas testing or pulse oximetry — a home reading alone, without physician documentation, does not establish insurance eligibility.

How to Get an Oxygen Concentrator Prescription: Steps and Documentation

Steps to obtain a prescription:

1. Physician documents qualifying SpO₂ levels (resting, exertional, and/or nocturnal)
2. Physician completes Certificate of Medical Necessity (CMS-484 for Medicare)
3. DME supplier is selected (in-network preferred for insurance coverage)
4. Equipment delivered, fitted, and patient educated on use and safety
5. Follow-up monitoring scheduled

What Flow Rate Do You Need for Your Oxygen Concentrator?

Flow rate (liters per minute, LPM) must match the prescribed oxygen requirement. Prescriptions specify flow rate based on clinical assessment.

Continuous vs. pulse dose:

⚠️ Pulse-dose concentrators are generally not appropriate for sleep use without physician clearance, as breathing rate and pattern during sleep may not reliably trigger adequate oxygen delivery [American Association for Respiratory Care, 2022].

Portable vs Home Oxygen Concentrator: Key Differences

Portability checklist:

• [ ] Prescription specifies continuous or pulse-dose delivery
• [ ] Prescribed flow rate is achievable by portable unit
• [ ] Battery duration sufficient for intended activity duration
• [ ] FAA approval confirmed if air travel is anticipated (verify against current FAA list)
• [ ] Weight and carrying method compatible with patient’s mobility

Best Portable Oxygen Concentrator for Air Travel (FAA-Approved)

The FAA maintains a list of portable oxygen concentrator (POC) models approved for use on commercial flights; a device not on this list cannot be used in-flight regardless of your prescription.

Before booking travel, confirm your specific POC model and battery configuration appear on the current FAA-approved list, since manufacturers periodically update models and the list itself is revised.

Airlines may also require advance notice (typically 48–72 hours) and a physician’s statement confirming you’re able to operate the device independently during the flight. Battery life should be planned for at least 1.5 times your total expected flight and layover time, since in-flight power outlets are not guaranteed.

Power, Battery, and Emergency Planning

Power outage safety note: Patients dependent on home oxygen concentrators should register with their local utility company as a medical priority customer and establish a backup plan with their DME provider. Consult your care team regarding emergency oxygen planning.

Renting vs Buying an Oxygen Concentrator

Oxygen concentrators require a prescription and are almost always obtained through a DME supplier — not purchased directly online. Your DME supplier will handle Medicare or insurance billing, deliver and set up the equipment, and schedule follow-up maintenance.

Your most important action: confirm your DME supplier is ACHC- or Joint Commission-accredited and is in-network with your insurance plan. → See our guidance on choosing a DME supplier

Managing Oxygen Therapy for a Loved One?

If you’re coordinating home oxygen therapy on behalf of a family member, here’s what to bring to the DME appointment: the physician’s Certificate of Medical Necessity (CMS-484 for Medicare), a copy of the qualifying SpO₂ test results, and your insurance information.

Ask the DME supplier specifically about backup oxygen planning and what to do in a power outage — this is required for safe home oxygen management.

The Cost of Getting It Wrong

Buying from an unlicensed seller, purchasing a CPAP without proper titration, or using an unvalidated pulse oximeter can have serious consequences: incorrect pressure settings can worsen sleep apnea rather than treat it; inaccurate pulse oximeters can mask dangerous oxygen drops; and purchasing from a seller that doesn’t verify your prescription means your insurance will not reimburse the cost. The sections below identify which purchasing channels are safe — and which to avoid.

What is an accredited DME supplier?

Durable medical equipment (DME) suppliers accredited by the Accreditation Commission for Health Care (ACHC) or The Joint Commission have met independent, third-party safety and quality standards. Accreditation is also what allows a supplier to bill Medicare and most private insurers directly on your behalf — an unaccredited supplier may require you to pay out of pocket and seek reimbursement yourself, which is slower and not guaranteed.

Recommended purchasing channels:

Channels and practices to approach with caution:

Patient communities like the r/CPAP forum and the COPD Foundation patient network are valuable resources for real-world device feedback — particularly on mask fit and long-term CPAP adherence. Our recommendations are consistent with the most frequently cited community insights: mask fit matters more than machine brand, and compliance data tracking is essential for insurance coverage continuity.

What to verify before any purchase:

• [ ] FDA 510(k) clearance or De Novo authorization (search FDA 510(k) database)
• [ ] Seller requires valid prescription where legally required
• [ ] Manufacturer’s warranty applicable to U.S. purchasers
• [ ] Return/exchange policy for items that do not fit or function as expected
• [ ] Compatibility with current prescription settings (CPAP, oxygen)

Pulse Oximeter — Maintenance Summary:

CPAP Machine — Maintenance Schedule:

OOP = out-of-pocket costs if not covered by insurance. Most insurers cover CPAP resupply on a schedule. Confirm with your plan.

Download the Free First-Time CPAP Buyer Checklist (PDF)

Get a one-page printable checklist covering your sleep study prep, prescription documentation, DME appointment, mask fitting, insurance paperwork, and first-week setup. Sent directly to your inbox

Nebulizer — Maintenance Schedule:

Cleaning frequency: Nebulizer components in contact with medication should be cleaned after each use per manufacturer instructions and standard infection control guidelines [CDC, 2023]. Failure to clean components may result in medication contamination and increased infection risk.

Oxygen Concentrator — Maintenance Overview:

MISTAKE 1: “Buying a consumer pulse oximeter for clinical monitoring”

Consumer devices (including many smartwatch sensors) are not FDA-cleared for clinical accuracy and may give false readings across certain skin tones. If your physician has ordered SpO₂ monitoring, ask specifically for a 510(k)-cleared device.

MISTAKE 2: “Buying a CPAP without proper titration”

A CPAP machine set to the wrong pressure can be ineffective or even harmful. Never purchase a CPAP without a valid prescription that specifies your pressure settings — and never use a used machine set to a previous owner’s pressure.

MISTAKE 3: “Ordering from a seller that doesn’t require a prescription”

Any online retailer selling CPAP machines without verifying your prescription is operating outside U.S. law [21 CFR 868.5965]. These devices will not be covered by insurance and may not be the device your physician prescribed.

MISTAKE 4: “Skipping mask fitting and accepting the first option”

Mask fit is the #1 factor in CPAP adherence. A poorly fitted mask causes leaks, skin irritation, and often leads to abandoning therapy entirely. Always request a fitting session, and ask about the exchange policy before committing.

MISTAKE 5: “Assuming insurance will cover the full cost automatically”

Coverage requires documentation (prescription, sleep study results, Letter of Medical Necessity), in-network supplier selection, and ongoing compliance reporting for CPAP. Skipping any step can result in denied claims and unexpected bills.

MISTAKE 6: “Buying a mesh nebulizer without checking medication compatibility”

Ultrasonic vibration in mesh nebulizers can degrade certain medications (particularly corticosteroids and some antibiotics). Always confirm compatibility with your prescribing physician and the device manufacturer before purchasing

MISTAKE 7: “Using a portable oxygen concentrator during sleep without physician clearance”

Pulse-dose concentrators may not deliver adequate oxygen during sleep, when breathing rate and pattern change. Confirm with your physician whether continuous-flow delivery is required for overnight use.

References

• American Academy of Sleep Medicine (AASM). International Classification of Sleep Disorders, 3rd Edition (ICSD-3), Text Revision. 2023.
  
• U.S. Food and Drug Administration. Pulse Oximeters — Safety Communication. 2021. https://www.fda.gov/medical-devices/safety-communications/pulse-oximeter-accuracy-and-limitations-fda-safety-communication
  
• U.S. Food and Drug Administration. Proposed Rule: Performance Standards for Pulse Oximeters. February 2024. https://www.fda.gov
  
• Nocturnal Oxygen Therapy Trial Group. “Continuous or nocturnal oxygen therapy in hypoxemic chronic obstructive lung disease.” Annals of Internal Medicine. 1980;93(3):391–398.
  
• Medical Research Council Working Party. “Long-term domiciliary oxygen therapy in chronic hypoxic cor pulmonale complicating chronic bronchitis and emphysema.” Lancet. 1981;1(8222):681–686.
  
• Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention. 2023. https://ginasthma.org
  
• World Health Organization (WHO). COVID-19: Clinical Management. 2022. https://www.who.int
  
• ISO 80601-2-61:2017. Medical electrical equipment — Particular requirements for basic safety and essential performance of pulse oximeter equipment. International Organization for Standardization.
  
• Pépin JL, Muir JF, Gentina T, et al. “Pressure reduction during exhalation in sleep apnea patients: a randomized crossover trial.” Chest. 2009;135(3):702–709.
  
• Mador MJ, Krauza M, Pervez A, et al. “Effect of heated humidification on compliance and quality of life in patients with sleep apnea using nasal continuous positive airway pressure.” Chest. 2005;128(4):2151–2158.
  
• Centers for Medicare & Medicaid Services (CMS). Local Coverage Determination (LCD): Oxygen and Oxygen Equipment (L33797). Current revision. https://www.cms.gov
  
• American Association for Respiratory Care (AARC). Clinical Practice Guideline: Oxygen Therapy for Adults in the Acute Care Facility. 2022. https://www.aarc.org
  
• Centers for Disease Control and Prevention (CDC). Guideline for Disinfection and Sterilization in Healthcare Facilities. 2023. https://www.cdc.gov
  
• U.S. Food and Drug Administration. Code of Federal Regulations, Title 21, Part 868 — Anesthesiology Devices. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-H/part-868