Our portable oxygen concentrator picks
Key Takeaways
- A portable oxygen concentrator provides extra oxygen for people with certain medical conditions who want to stay active.
- The price of portable oxygen concentrators starts at $2,500, but Medicare and private insurance cover part of the cost in some cases.
- Using a portable oxygen concentrator can help you maintain a healthy, active lifestyle even if you need supplemental oxygen.
A quick look at the best portable oxygen concentrators
- Best for Air Travel: Inogen One G5
- Longest Battery Life: CAIRE Freestyle Comfort
- Easiest to Use: Philips Respironics SimplyGo Mini
- Smallest: Inogen One G4
- Best Continuous Flow: O2 Concepts Oxlife Independence
If you’ve been prescribed supplemental oxygen by your doctor, using a portable oxygen concentrator, also called a portable oxygen machine, can be a convenient way to meet your oxygen needs while still getting out and doing all the things you enjoy.
It’s important to stay active even if you need extra oxygen. According to research published in the Journals of Gerontology, older adults who are socially active have better physical health and emotional well-being. [1] Fingerman KL et al. Variety is the Spice of Late Life: Social Integration and Daily Activity. The Journals of Gerontology. Jan. 18, 2019. Found on the internet at https://academic.oup.com/psychsocgerontology/article/75/2/377/5292329 Also, a 2021 study of more than 32,000 adults with chronic obstructive pulmonary disease (COPD) or certain types of lung diseases found that those who were physically active had longer lifespans and improved heart rates. [2] Shu CC, et al. The Ability of Physical Activity in Reducing Mortality Risks and Cardiovascular Loading and in Extending Life Expectancy in Patients With COPD. Scientific Reports. Nov. 4, 2021. Found on the internet at https://www.nature.com/articles/s41598-021-00728-2 A portable oxygen machine can help you stay active by providing safe, effective delivery of oxygen while you’re out and about.
But finding the best portable oxygen concentrator for your needs can be confusing—especially if you’re buying one for the first time. Our Reviews Team researched the top portable oxygen concentrators on the market. We dug into information on pricing, features, battery life, and more to help you find the best model for you.
Why you can trust our expert review
Our Reviews Team recommends products and services we believe provide value in the lives of our readers. We’ve spent more than 1,000 hours carrying out in-depth research on each oxygen concentrator to give you the most accurate review. To make our selections, we:
- Engaged in independent research
- Consulted with geriatric care and respiratory medicine experts
- Mystery shopped more than 15 brands and 30 models of oxygen machines
- Surveyed 600 oxygen machine users and caregivers of oxygen machine users
- Reviewed academic research into the efficacy of portable oxygen concentrators
- Read real reviews from verified customers on trusted third party websites, such as the Better Business Bureau (BBB) and Trustpilot
How we chose the best oxygen concentrators
Our Reviews Team consulted with geriatric care experts to learn more about portable oxygen concentrators (POCs) and how they can enhance users’ quality of life.
Based on our expert consultations, user survey, and own research, we determined the following factors to be important for our readers when shopping for a POC unit:
- Cost
- Ease of use
- Oxygen delivery method
- Number of settings
- Weight
- Battery life
- Time to recharge battery
- Warranty
- Availability (all devices available online or in brick-and-mortar stores)
We had all of our selections medically reviewed by an expert in the field to ensure that each brand and model is appropriate for our readers’ needs.
Table 1 Comparison of the best portable oxygen concentrators
Brand | Inogen One G5 | CAIRE Freestyle Comfort | Philips Respironics SimplyGo Mini | Inogen One G4 | O2 Concepts Oxlife Independence |
---|---|---|---|---|---|
Cost | $2,882–$3,586 | $2,995 | $2,595 | $2,650–$3,344 | $2,850 |
Weight (pounds)* | 4.7–5.7 | 5–6 | 5–6 | 2.8–3.3 | 16.7 |
Dimensions (width x depth x height, in inches) | 7.2" x 3.3" x 8.2" | 7.3" x 3.1" x 10" | 8.3" x 3.6" x 9.4" | 5.9" x 2.7" x 7.2" | 10.9" x 8" x 20.2" |
Flow type | Pulse | Pulse | Pulse | Pulse | Continuous |
Battery life (hours)† | 6.5–13 | 8–16 | 4.5–9 | 2.25–5 | 1.5–5.25 |
Battery charging time (hours)* | 4–8 | 3.5–6 | 4–8 | 3.3–6 | 1.5–2.5 |
Range of flow settings (liters per minute) | 1–6 | 1–5 | 1–5 | 1–3 | 0.5–3 continuous; 0.5–6 pulse |
Max oxygen output (liters per minute) | 1.26 | 1.05 | 1 | 0.63 | 3 |
Noise level (decibels)† | 39 | 39 | 43 | 40 | 40 |
FAA approval (permitted on airplanes) | Yes | Yes | Yes | Yes | Yes |
Warranty (years) | 3 | 3 | 3 | 3 | 5 |
* Varies depending on use of single or single and extended battery
† Varies depending on flow setting
Best portable oxygen concentrators in 2023
Oxygen Concentrator Store customer service
All of the brands and models in this review are available through the online retailer Oxygen Concentrator Store. You can contact its customer service department in the following ways:
- Phone: 844-885-9530, available 365 days a year on the following schedule:
- 6 a.m. to 9 p.m. MT Monday through Friday
- 7 a.m. to 7 p.m. MT Saturday
- 8 a.m. to 7 p.m. MT Sunday
- Email: service@amsrco.com
- Online chat: On the Oxygen Concentrator Store support page
- Contact form: Submit an online ticket, and a representative will respond within one business day.
The Oxygen Concentrator Store website also has a detailed product support page with information on cleaning, maintenance, and use of portable oxygen concentrators.
Our Reviews Team’s customer service experience
A member of our Reviews Team called the Oxygen Concentrator Store to learn more information about all of the brands and models in this list. It took less than 30 seconds to get a representative on the line, and he was friendly, helpful, and knowledgeable about every model we asked about.
He shared that all of the portable oxygen machines sold through Oxygen Concentrator Store come with a free seven-day trial period. If you find the unit you’ve purchased has mechanical problems, is hard to use, or just isn’t a good fit for you, simply call the store to receive a shipping label. Then you can send the unit back (at your own cost) and exchange it for a different one.
Shipping takes about three to five business days, but Oxygen Concentrator Store also offers two-day and overnight shipping.
After sharing details of the various models over the phone, the representative offered to email the information as well and gave us his direct phone number for any future questions.
He also said even if we didn’t buy a unit from Oxygen Concentrator Store, he would be happy to answer questions and provide help in the future. We were very pleased with the customer service experience; it felt like we were learning about portable oxygen concentrators rather than enduring a high-pressure sales call.
What is an oxygen concentrator?
An oxygen concentrator is a machine that concentrates oxygen from the air we breathe. It uses pumps, electricity, and filters to increase the amount of oxygen in the air from 21% to 90% or higher. Portable oxygen concentrators are powered by a rechargeable battery and can be taken with you to provide mobile oxygen on-the-go, whereas home oxygen concentrators need to be plugged into a power outlet and are meant for use in the home.
How does an oxygen concentrator work?
Oxygen concentrators convert outside air into almost pure oxygen with the following steps:
- Draws outside air into the unit
- Filters the air to remove any contaminants
- Compresses the filtered air
- Passes the filtered and compressed air through a sieve bed that extracts the nitrogen
The resulting air is about 95% oxygen, which flows from the machine through tubing connected to the machine on one end and to a nasal cannula or oxygen face mask on the other end.
For more information, the American Lung Association has a webpage with helpful videos showing how to use a portable oxygen concentrator. [7] American Lung Association. Getting Started with a Portable Oxygen Concentrator. Found on the internet at https://www.lung.org/lung-health-diseases/lung-procedures-and-tests/oxygen-therapy/getting-started-portable-oxygen-concentrator
Oxygen delivery/flow types
Portable oxygen concentrators deliver either a continuous flow of oxygen, measured in liters per minute (LPM), or a pulse flow (also called intermittent flow). Pulse flow delivery systems produce a puff of oxygen every time you breathe.
Some concentrators can deliver oxygen by either pulse or continuous flow, depending on the setting you choose. Other devices only provide one type of flow. For example, most portable concentrators (including all of the models in this review) offer only pulse flow settings.
ⓘ | It’s important to know which type of flow you need and the amount of oxygen (in LPM) your prescription is written for when buying a portable oxygen machine. If you’re unsure of these details, check with your health care provider. |
Traveling Safely with Portable Oxygen
Traveling with an oxygen machine requires careful preparation to ensure your health and safety. Here are condensed tips for different modes of travel:
General Tips:
- Consult your healthcare provider before traveling to address potential complications.
- Stay hydrated during your journey, especially on long flights.
Travel Checklist:
- Ensure necessary certificates/documentation.
- Contact the travel carrier to understand their policies and make arrangements.
- Carry a copy of your oxygen prescription and contact info.
- Bring sufficient battery power, including spares.
- Pack necessary accessories and adapters.
- Arrive early for flights.
- For car travel, have a companion, charge batteries, and avoid extreme temperatures.
- Secure oxygen equipment while driving.
- For bus travel, check policies, charge batteries, and pack extra accessories.
- For train travel, review policies, charge batteries, and carry extra accessories.
- For cruise travel, arrange equipment rental, review cruise line policies, and keep documentation handy.
What is a continuous flow oxygen concentrator?
Continuous flow portable oxygen concentrators offer a consistent flow of oxygen, while pulse flow portable oxygen concentrators provide oxygen every time you inhale, according to an article published in the journal Breathe. [4] Hardavella, G, et al. Oxygen Devices and Delivery Systems. Breathe. 2019. Found on the internet at https://breathe.ersjournals.com/content/15/3/e108 Continuous flow oxygen is often recommended for people who require a high oxygen flow, which is roughly 3 liters per minute or more, according to the American Thoracic Society. [5] Jacobs SS, Krishnan JA. Patients Choose Hypoxemia Over Social Isolation. Annals of the American Thoracic Society. September 2021. Found on the internet at https://www.atsjournals.org/doi/full/10.1513/AnnalsATS.202106-676ED Ask your doctor if you would benefit from a high-flow oxygen concentrator.
Most portable oxygen concentrators offer both pulse dose and continuous flow delivery. If your health care provider has recommended a continuous flow portable oxygen concentrator, you have options.
Table 2 Compare Continous Flow Oxygen Concentrators
O2 Concepts Oxlife Independence | CAIRE SeQual Eclipse | Respironics SimplyGo | |
---|---|---|---|
Cost | $2,850 | $3,200 | $2,500 |
Weight (pounds) | 16.7 | 18.4 | 10 |
Dimensions (width x depth x height, in inches) | 10.9” x 8” x 20.2” | 7.1” x 12.3” x 19.3” | 10” x 6” x 11.5” |
Machine type | Portable | Portable | Portable |
Battery life (hours) | 5.25 | 3.7 | 2.9 |
Battery charging time (hours)* | 1.5–2.5 | 1.8–5 | 2–3 |
Range of flow settings (liters per minute) | 0.5–3 | 0.5–3 | 0.5–2 |
Maximum oxygen output (liters per minute) | 3 | 3 | 2 |
Oxygen purity level | 87–93% | 87–95% | 87–96% |
Noise level (decibels) | 40 | 48 | 43 |
Warranty (years) | 5 | 3 | 3 |
* Varies depending on use of single or single and extended battery
How do continuous oxygen concentrators work?
Continuous flow oxygen concentrators deliver the same consistent amount of oxygen. This makes them different from pulse flow oxygen concentrators. Pulse flow concentrators deliver a small dose, or “pulse,” of oxygen every time you take a breath. If your breathing rate increases, a pulse flow portable oxygen concentrator will respond with a higher flow rate by delivering more oxygen to meet your body’s needs. Between each inhalation, the machine doesn’t deliver oxygen. A continuous flow oxygen machine will give the same amount of oxygen no matter what—your breathing rate doesn’t affect delivery.
“Pulse flow is best described as drinking water with a straw, where the delivery is more controlled and individualized per need,” explained Danielle Jason, an oxygen specialist, in an article she authored for the Oxygen Concentrator Store. “A continuous flow machine is [more like] drinking water out of a water fountain. When you turn on a water fountain, water streams out at a somewhat steady pace.” [6] Jason D. Pulse vs. Continuous Flow. Oxygen Concentrator Store. May 23, 2023. Found on the internet at https://www.oxygenconcentratorstore.com/blog/pulse-vs-continuous-flow
Continuous flow oxygen delivery is the most common form of oxygen delivery. Home oxygen concentrators offer only continuous flow, while many portable oxygen concentrators may offer the option to choose between pulse or continuous flow oxygen delivery. Currently, there aren’t any POCs that deliver portable oxygen with continuous flow only; POCs are either dual flow or pulse flow only.
Who should use a portable oxygen concentrator?
If you need supplemental oxygen (also known as oxygen therapy), you’re not alone. The American Thoracic Society estimates 1.5 million adults in the United States use oxygen therapy. [8] Annals of the American Thoracic Society. Optimizing Home Oxygen Therapy: an Official American Thoracic Society Workshop Report. Found on the internet at https://www.atsjournals.org/doi/10.1513/AnnalsATS.201809-627WS
People with a variety of conditions may benefit from supplemental oxygen. According to the American Lung Association, these conditions include: [9] American Lung Association. Oxygen Therapy. Found on the internet at https://www.lung.org/lung-health-diseases/lung-procedures-and-tests/oxygen-therapy
- Chronic obstructive pulmonary disease (COPD)
- Pulmonary fibrosis
- Emphysema
- Pneumonia
- Severe asthma
- Cystic fibrosis
- Sleep apnea
- Anemia
When your body is not getting enough oxygen, you might feel confused, weak, tired, or breathless. Low oxygen levels can also cause other health problems over time, according to the National Institutes of Health (NIH). [10] National Institutes of Health. Oxygen Therapy. Found on the internet at https://medlineplus.gov/oxygentherapy.html Supplemental oxygen can help relieve these symptoms and improve your overall health.
If you have a diagnosed need for extra oxygen but don’t want to be tied to a stationary, in-home oxygen unit, you may enjoy the independence and freedom a portable oxygen concentrator can give you. Being able to go out with friends and family, travel, and/or enjoy activities outside of the house are all possible with portable oxygen concentrators.
Because portable units are designed to be lightweight, they aren’t as powerful as stationary, home oxygen machines. As a result, the best portable oxygen concentrators currently on the market can only provide an oxygen output of up to 3 LPM. If your prescription is written for more than this amount, a portable unit won’t meet your needs, so you’ll need to look for an in-home oxygen system instead.
Many portable oxygen concentrators weigh fewer than five pounds and can be worn as a shoulder bag or backpack, allowing you to do all of your normal activities while getting the oxygen you need. Heavier oxygen machines—like the Inogen One G5 with a double battery—can also be strapped onto a mobile cart and rolled like a suitcase.
What to look for in a portable oxygen concentrator
The best portable oxygen concentrators vary in their maximum amount of oxygen output (measured in liters per minute), type of oxygen flow (continuous or pulse), weight, noise level, battery life, and warranty. You’ll need to think about each factor as you’re deciding which model is the best for your needs.
Current oxygen needs
Your oxygen needs are the first place to start when shopping for portable oxygen concentrators. Check your prescription to see what your doctor has written for oxygen amount and type of flow.
Future oxygen needs
It’s also a good idea to think about your future oxygen needs. You may only need one LPM now, but if you have a chronic disease like COPD, you may want to choose an oxygen concentrator that’s best for COPD, with a maximum output that’s above your current needs. This way you won’t need to replace your concentrator with a more powerful one if your oxygen needs increase.
Battery life
Before narrowing down your choices, consider how long you’ll need to use your portable oxygen concentrator when you leave the house. Do you only go out to run quick errands, or do you enjoy spending full days out of the house? Do you enjoy traveling? These are all factors that will affect which battery-operated concentrator is the best fit for you.
Warranty length and type of coverage
Warranties vary among manufacturers of portable oxygen concentrators, both in terms of length and what they cover. One thing to ask about is when the warranty starts. Some companies begin their warranty on the date the unit is put on a store’s shelves (whether brick-and-mortar or online), not when it arrives at your house.
For example, if a portable oxygen concentrator has been sitting on the shelf for three months before you buy it, you may have lost three months of your warranty. Other companies don’t start the warranty period until you purchase the unit, and this is obviously better for you as the customer.
How much do portable oxygen concentrators cost?
Portable oxygen concentrators cost between $4,000 and $4,500 from the manufacturer, although you can often find them in the range of $2,500 to $4,000 from online retailers such as the Oxygen Concentrator Store and others. Used portable oxygen concentrators are even less expensive, at a cost of $800 to $2,000.
Online retailers like the Oxygen Concentrator Store may have financing and “buy now, pay later” payment options through services like CareCredit, PayPal, or Affirm that allow you to finance your portable oxygen concentrator purchase and pay it off over time.
Does Medicare cover portable oxygen concentrators?
Oxygen concentrators are considered durable medical equipment (DME) ⓘMedical equipment expected to last at least three years, prescribed for in-home use for a medical reason., and as such they’re covered under Medicare Part B if certain criteria for medical necessity are met. Medicare will cover the cost of renting oxygen equipment and accessories under the following conditions: [11] Medicare.gov. Oxygen Equipment and Accessories. Found on the internet at https://www.medicare.gov/coverage/oxygen-equipment-accessories
- You have a prescription from a doctor listing your need for supplemental oxygen (either a specific medical condition or a statement that oxygen therapy may improve your health)
- You have been diagnosed with low blood oxygen levels (hypoxemia) through a test conducted by your doctor or other health care provider (not an oxygen equipment supplier)
- Other measures to raise your blood oxygen levels haven’t been successful
Your doctor will be required to complete paperwork and provide documentation on the medical necessity of a portable oxygen concentrator. If you have questions about this requirement, your local State Health Insurance Assistance Program (or SHIP), can help. You can find your local SHIP counselor at www.shiphelp.org.
Medicare providers may pay for portable oxygen concentrator rentals on a case-by-case basis if they decide it would be beneficial for you either as a sole source of oxygen or as a supplement to an in-home unit. [12] Centers for Medicare and Medicaid Services. Home Use of Oxygen. Found on the internet at https://www.cms.gov/medicare-coverage-database/view/ncd.aspx?NCDId=169
Keep in mind Medicare will not cover the purchase of a portable oxygen concentrator, only the rental. See Medicare.gov for more information.
If you purchase a portable oxygen concentrator, Medicare will help pay for certain types of oxygen-related supplies and services such as:
- Tubing, masks, and nasal cannulas (nose tubes)
- Maintenance and repairs
After you meet your deductible for the year, you will only pay 20% of the Medicare-approved cost of those supplies. [11] Medicare.gov. Oxygen Equipment and Accessories. Found on the internet at https://www.medicare.gov/coverage/oxygen-equipment-accessories
Oxygen Concentrator Store does not bill Medicare directly, so that’s something you’ll have to handle.
Does insurance cover portable oxygen concentrators?
Some private insurance companies will pay for part or all of the costs of oxygen concentrators, but plans vary quite a bit. Contact your insurance provider to see what your plan covers.
You can also use NCOA’s Benefits CheckUp tool to see what other discounts and savings you qualify for.
How to save money on oxygen machines
If you are in need of supplemental oxygen, also called oxygen therapy, you may be concerned about the expense of owning and using an oxygen tank, concentrator, or CPAP machine. Thankfully, you can save money on these units in a variety of ways.
Buy a used oxygen concentrator
If you can’t afford to purchase a new oxygen concentrator, consider looking for a used one from your local DME provider. They typically run between $800 and $2,000, which is about a third of the cost of new units. Oxygen Concentrator Store also sells used portable oxygen concentrators.
Used portable oxygen concentrators start at $995, which can be a third of the cost of new units.
Christopher Norman, a New York-based nurse practitioner who specializes in geriatric care (the care of older adults) and holistic health, gave the following tips for people thinking about buying a used portable oxygen concentrator. “As with anything you might buy, I would always advise asking about the equipment’s history. Was it maintained appropriately [and] cleaned regularly (oil-based cleaners can gum up the works, whereas water-based cleaners are usually safe); what kind of environment was it maintained in (smoking household, lots of pets, etc.); has it ever been serviced and by whom; and what is its purchase history (maybe you’re actually getting it third or fourth hand)? I would advise a person to never buy used tubing (the nasal cannula) or used filters due to risk for infection or other transmissible illness concerns,” said Norman.
Rent an oxygen concentrator instead of buying one
Some people need supplemental oxygen and already have an in-home unit, but they may want to rent a portable oxygen concentrator for an upcoming trip or other time away from home. Or you may want to rent a unit for a few weeks to see if it’s a good fit for your needs.
While renting may not be a good choice if you have a long-term requirement for oxygen therapy, it could be a great fit for someone who needs an oxygen concentrator temporarily. This may include people who are recovering from COVID-19, pneumonia, or another short-term respiratory illness.
Not all oxygen concentrators are available to lease, but certain models are. For example, the Oxygen Concentrator Store offers Inogen and Respironics units for rental starting at $210 per week.
Renting can save you thousands of dollars up front, especially considering Medicare Part B will pay for the rental of oxygen concentrators—as well as some other types of oxygen equipment. [11] Medicare.gov. Oxygen Equipment and Accessories. Found on the internet at https://www.medicare.gov/coverage/oxygen-equipment-accessories
Talking to your doctor about how long you’ll need to use supplemental oxygen can help you decide whether it’s best to rent or buy an oxygen machine.
How long do portable oxygen concentrators last?
Most concentrators last three to five years before needing to be replaced.
Bottom line
Supplemental oxygen is sometimes necessary for relieving symptoms of a respiratory or cardiac disease and improving a person’s quality of life. If you are facing the need for oxygen therapy, know that it doesn’t mean your normal activities have to end!
For those who value ease of use, we rated Philips Respironics SimplyGo Mini as “Easiest to Use.” If you’re looking for a POC that’s easy to carry, we selected the Inogen One G4 as “Smallest Portable Oxygen Concentrator.” If you’re a frequent flier, the Inogen One G5, which we ranked as “Best for Air Travel”, may be a good choice. For those who want to ensure their POC can function as long as possible between charges, we chose the CAIRE Freestyle Comfort as “Best Battery Life.” Consider the O2 Concepts Oxlife Independence for a continuous flow portable oxygen concentrator with the option for battery and plug-in power options.
You can—and should—continue to enjoy outings with your family and friends, and the best portable oxygen concentrator will go a long way in helping you do that.
Frequently asked questions
Have questions about this review? Email us at reviewsteam@ncoa.org.
Sources
- Fingerman KL, et al. Variety is the Spice of Late Life: Social Integration and Daily Activity. The Journals of Gerontology. Jan. 18, 2019. Found on the internet at https://academic.oup.com/psychsocgerontology/article/75/2/377/5292329
- Shu CC, et al. The Ability of Physical Activity in Reducing Mortality Risks and Cardiovascular Loading and in Extending Life Expectancy in Patients With COPD. Scientific Reports. Nov. 4, 2021. Found on the internet at https://www.nature.com/articles/s41598-021-00728-2
- International Noise Awareness Day. Common Noise Levels – How Loud is Too Loud? Found on the internet at https://noiseawareness.org/info-center/common-noise-levels/
- Hardavella G, et al. Oxygen Devices and Delivery Systems. Breathe. 2019. Found on the internet at https://breathe.ersjournals.com/content/15/3/e108
- Jacobs SS, Krishnan JA. Patients Choose Hypoxemia Over Social Isolation. Annals of the American Thoracic Society. September 2021. Found on the internet at https://www.atsjournals.org/doi/full/10.1513/AnnalsATS.202106-676ED
- Jason D. Pulse vs. Continuous Flow. Oxygen Concentrator Store. May 23, 2023. Found on the internet at https://www.oxygenconcentratorstore.com/blog/pulse-vs-continuous-flow
- American Lung Association. Getting Started with a Portable Oxygen Concentrator. Found on the internet at https://www.lung.org/lung-health-diseases/lung-procedures-and-tests/oxygen-therapy/getting-started-portable-oxygen-concentrator
- Annals of the American Thoracic Society. Optimizing Home Oxygen Therapy: an Official American Thoracic Society Workshop Report. Found on the internet at https://www.atsjournals.org/doi/10.1513/AnnalsATS.201809-627WS
- American Lung Association. Oxygen Therapy. Found on the internet at https://www.lung.org/lung-health-diseases/lung-procedures-and-tests/oxygen-therapy
- National Institutes of Health. Oxygen Therapy. Found on the internet at https://medlineplus.gov/oxygentherapy.html
- Medicare.gov. Oxygen Equipment and Accessories. Found on the internet at https://www.medicare.gov/coverage/oxygen-equipment-accessories
- Centers for Medicare and Medicaid Services. Home Use of Oxygen. Found on the internet at https://www.cms.gov/medicare-coverage-database/view/ncd.aspx?NCDId=169