If you struggle to breathe through your nose or require a higher flow of oxygen, a full face mask may be a better option. Full face masks are also recommended for those who primarily breathe through their mouth during sleep.

Our mask sizing guides can be found on their product pages under the tab "Product guides". Each guide can be printed out and used to measure against your facial features.

When possible, we suggest ordering a Fit Pack, which comes with multiple cushion sizes so you can find your perfect full face fit every time. If you have to over-tighten your mask to keep a secure seal or you're experiencing air leaks or irritation, try another size.

And remember, if your mask doesn't fit right or you don't love it, you can return it for a refund, and we'll help you find a better one with our 60-Night Mask Fit Guarantee.

If you can breathe through your nose, we suggest trying a nasal pillow or nasal cradle mask, like the AirFit P10 or N30. These masks offer minimal facial footprints with a compact design that won't get in the way when you lay your head against a pillow.

Customers who breathe through their mouth should look for an under-the-nose full face mask like the AirFit F40, which also features a low-profile fit with a compact cushion that stays sealed in any sleeping position.

Active side sleepers will appreciate ResMed's AirFit 30i line. Each of these masks has the same minimal footprints and compact designs as other masks we've mentioned above, but with a full swivel hose connection that sits at the top of the head to eliminate hose tangling and mask pulling. Look for the AirFit F30i, AirFit N30i, and AirFit P30i.

You'll want to choose a full face mask that delivers air through your nose and mouth.

If you're new to CPAP therapy or struggling to get used to your CPAP mask, we suggest trying the AirFit F40, which features a low-profile under-the-nose design with a secure seal.

Those who require higher pressure therapy may want to go with the AirFit F20, which has a traditional over-the-nose design that's been proven to fit over 97% of customers.

Your AirSense 11 replacement parts should be changed out on schedule to protect your health and the life of your CPAP machine. Be sure to watch for signs of wear, such as discoloration, cracking, bad odor, and air leaks.

• Water Chamber: Replace every 3-6 months
• Hose: Replace every 3-6 months
• Filter: Replace every 1-3 months