The AirMini by ResMed, the HDM Z2 by Breas Medical, the Transcend 3, and the new Transcend Micro are mighty travel CPAPs loaded with features. Let’s examine the similarities and differences among these machines in detail.

Here’s a table that will give you a bird’s eye view of these machines side by side.

AirMini, HDM Z2, Transcend 3 miniCPAP Auto, and Transcend Micro Travel APAP Comparison Chart

ResMed AirMiniHDM Z2 AutoTranscend 3 miniCPAP AutoTranscend Micro
Release DateMay 2017Mar 2019July 2019July 2022
Dimensions (Size)5.4 x 3.3 x 2.1 inches6.48 x 3.30 x 2.02 inches7.4 x 3.7 x 3.7 inches3.6 x 3.6 x 2.4 inches
Footprint17.82 sq inches21.39 sq inches27.38 sq inches12.96 sq inches
Volume37.4 cubic inches43.2 cubic inches101.3 cubic inches31.1 cubic inches
Weight10.6 Oz10.4 Oz10.4 Oz7.74 Oz
HumidificationHumidX & HumidX Plus Heat Moisture Exchangers (HME)Waterless – Heat and Moisture Exchanger capsuleNo humidifierHeat and Moisture Exchanger filters
Quietness (Noise level)30 dBA26 dBA26 dBA27 dBA (± 2 dBA)
Operating Pressure Range4-20 cm H2O4-20 cm H2O4-20 cm H2O4-20 cm H2O
Power100-240V, 50-60Hz100-240V, 50-60Hz100-240V, 50-60Hz100-240V, 50-60Hz
Integrated BatteryNoOptional (at $359 extra)NoNo
Ramp Time 0-45 minutes0-45 minutes0-45 minutes0-45 minutes. + 25% time variance
Mobile Device AppMyAir (Apple 4.6 stars, Android 4.4 stars)Nitelog (Apple 1.5 stars, Android 2 stars)TranSync for CPAP (1 star in Apple Store)MySleepDash (Apple+Android, new app, not rated yet)
Altitude AdjustmentAutomatic up to 8500 Feet (2591 m)Automatic up to 8000 Feet (2438 m)Automatic up to 8000 Feet (2438 m)Automatic up to 8000 Feet (2438 m)
Leak CompensationYesYesYesNo
For Her ModeYesNoNoNo
Expiratory Pressure ReliefYes (EPR)Yes (Z-Breathe)Yes (EZEX)Yes (EZEX)

AirMini, Z2, Transcend 3, Transcend Micro – Size and Weight

Three of the machines (all besides the Micro) weigh similarly at just over 10 oz and are already feather-light, which is what you want in a travel CPAP.

Of course, the Transcend Micro introduced a brand new level of lightness to the world of travel CPAP. It weighs just under 8 oz. So, make sure you actually have it in your bag or purse before you step out the door because you’ll barely feel its absence in case you forget to take it with you. 

Until the release of the Transcend Micro, the AirMini was the smallest travel CPAP on the market. But, in fact, all four machines are very small. If you glance at the chart above, you’ll see that the Transcend 3 has the largest footprint at just over 27 sq inches. But even then, it is only slightly larger than the HDM Z2

So, despite some differences in footprint, all four machines are small and easily portable. However, when you look at the volume that each machine occupies in your bag, you’ll notice quite a contrast between the Transcend 3 and the other three machines. 

(Please note that the actual volume each unit occupies is smaller than the number given in the table above because these machines are not solid rectangular blocks but have rounded shapes and curves.)

So, if your carry-on luggage space is limited, this is something to consider since the overall volume of the Transcend 3 is nearly three times that of either the AirMini or the Micro. It’s 2.5 times the volume of the Z2. 


The AirMini, the Z2, and the Micro feature integrated waterless humidification. All three use Heat Moisture Exchange (HME) technology. HME filters seize the heat and moisture of your breath and return it to your airways. 

Although not a full substitute for a regular humidifier, HME does the job for a time. Note that HME filters need to be replaced every week and don’t work as well when wet. They are designed to be replaceable and are used in healthcare settings to provide short-term humidity.

Ironically, unlike the other three machines, and being the largest of the four units, the Transcend 3 does not have the humidification feature.

Comfort Features

All four machines have both manual CPAP and AutoPAP functionality. This means that they can provide both static and variable pressure during a night of sleep. 

All four machines offer these comfort features:

  • Ramping
  • EPR (Expiratory Pressure Relief)

Ramping starts you off at a lower pressure and only begins to increase it after a period that you can set – up to 45 minutes on each of the machines. This means that you can fall asleep comfortably at a lower pressure and only then have your prescribed pressure applied.

AutoRamp takes this feature a step further by detecting when you have fallen asleep and only then beginning to increase the pressure. AirMini is the only machine in this lineup that offers AutoRamp. 

Expiratory Pressure Relief makes your CPAP therapy even more comfortable by lowering the air pressure at exhalation. This feature is present in all four machines – under different names. ResMed calls it EPR on the AirMini. It is Z-Breathe on the Z2. And EZEX is the name of the feature on the Transcend machines. 

Leak compensation is another comfort feature designed to make your night’s sleep even smoother. It detects any mask leak rises during the night and increases air pressure to compensate for the loss. 

Three of the machines – AirMini, HDM Z2, and Transcend 3 – offer leak compensation. The feature is not available on the Micro. 

Bluetooth Connectivity

All four machines can connect to smartphones via Bluetooth. Each of the machines has an app that enables you to read data and make adjustments. 

Importantly, please note that the only way to adjust your comfort settings on the AirMini is via the myAir app.

If you want to change comfort settings on either of the Transcend machines, you need to download the Transcend software onto your PC and connect the machine to the computer using a USB-C cable. You must use the software to change the settings.

The Z2 is the only machine where you can adjust comfort settings directly on the unit. 

Without getting into all the features of each sleep app, we’ll mention an important consideration. 

The myAir app is rated at an average of 4.5 stars in the Apple Store and Google Play. The Z2’s Nitelog enjoys only 1.75 stars. 

The TranSync for CPAP app for Transcend 3 has a 1-star rating in the Apple Store. And finally, the MySleepDash that connects with the Micro is available for both Apple and Android, but it’s a new app, so it has not been rated yet.

Noise Level

The smaller the machine, the more noise it generally produces. This is due to the lack of space within the machine for sound-muffling padding. 

The Z2 is a newer and slightly bigger machine than the AirMini, so its technology enables it to operate more quietly. 

The noise level of the Transcend 3 is identical to the Z2 at 26 decibels. And finally, the Transcend Micro operates at 27 decibels, give or take two decibels. Our Sleep Science Coach Susan found the Micro to be just a little louder than machines that run at 26 decibels. 

Please keep in mind that the Micro comes with a muffler kit that will help mitigate some of the noise if you happen to be sensitive to sound. 

Battery Options

Batteries are available for each of the four machines. Please note that only the Z2 offers an integrated battery unit. But let’s explore the available battery options. 

First, let’s introduce the Zopec Voyage CPAP Battery. It is universal and works with any CPAP machine. It can be connected to each of our travel machines directly – no adapter cable is needed.

In addition, each of the machines has other battery options.

The Z2 has an option for the Powershell battery module. This is the only integrated power module available among our travel CPAPs. You can purchase it when ordering the Z2 for some savings, or you can buy it later. 

The AirMini can also be powered by the Medistrom Pilot-24 battery. If you wish to connect it to your car cigarette lighter, you will also need the 65W ResMed AirMini DC/DC Converter.

The Transcend machines can be powered by their native Transcend Travel Multi-Night CPAP Battery

ResMed AirMini DC/DC Converter - 65W

Finally, as mentioned before, the Zopec Voyage is compatible and works really well with all machines in our lineup (and with any other CPAP), so it is a great complement to your CPAP therapy in case you ever need an additional power source. 

The For Her Mode

The AirMini is the only machine in the lineup that offers the AutoSet For Her mode of operation that is specifically designed for women. The For Her algorithm is more sensitive to flow limitation and responds faster to provide for a smoother and deeper quality of sleep for women. 

Other Features

All four units have universal power at 100-240V, and 50-60Hz, which means that you can use them anywhere in the world. You may only need a plug adapter because power outlets can vary depending on where you travel. 

Medili Universal Travel Charger Adapter Plug

However, you don’t have to buy a power converter, and those can add needless weight. 

All four units operate within a Pressure Range of 4-20 cm H2O. All four are also equipped with automatic altitude adjustment of 8,500 ft (AirMini) and 8,000 ft (Z2 and the Transcend machines). 

Our Verdict

So, which machine is ideal for you? 

Generally speaking, you should buy a machine that best fits your needs. And if the price is a big factor, please keep in mind that when you purchase your CPAP from Respshop, you’re getting your machine at a discount from a reputable vendor. 

Now, the price gap between the priciest machine, the AirMini, and the least expensive one, the Transcend 3 miniCPAP Auto, is about $280. That said, the Transcend 3 is the only machine in the lineup that does not offer humidification. So, if your mouth, nose, or airways tend to become dry and irritated, then perhaps it’s best to opt for one of the other three units. 

Two features that are exclusive to the AirMini are AutoRamp and the For Her mode. So, if you are a lady, and you want your machine to detect when you have fallen asleep before it starts increasing the pressure, you should probably strongly consider the AirMini. 

In addition, if you want to monitor your sleep data, you’ll probably find the MyAir app easier to use than at least two of the other apps, based on the ratings. 

Though the Transcend Micro is new to the market, reviews are beginning to trickle in, and people seem to love it. So, if you like the idea of a super compact yet mighty travel CPAP, then perhaps you should take a closer look at the Micro. 

As for the Z2, you’ve probably noticed that it is a worthy competitor of the AirMini and comes with some savings. 

And whichever machine you end up choosing, sleep tight!