*The sizing on these is wrong. I wear a medium (F20) mask and the large covers just barely fit.*
If you wear a large mask I would definitely look elsewhere. Please size up on these covers.

That being said: my F20 foam mask without a cover is very comfortable and has a perfect seal. Using these covers is a bit of a challenge because they just barely fit, and the seal is definitely not as good as without them, but if it means I don't have to replace my $50 mask as often, I still think it's worth it.

They seem to fit and work better than thicker covers I've seen. I wash these frequently and replace my mask cover every night. I am prone to acne, mask-ne, drooling due to allergies, reflux, and irritation from the mask and headgear though, so your mileage may vary. I wash these with my regular laundry and they are fine. They will hold up better if you wash by hand as recommended, but I'm not going to do that!

They are insanely overpriced for what they are: thin pieces of cloth. If you are remotely handy with a sewing machine you could probably make better ones.

I have used this liner on my mask for multiple months, and it is a weird thing; it either works extremelly well, or it causes leaks that I have the most difficult time adjusting for. When I first put it on, I kept messing with it, rearranging it, and trying to adjust it; but my mask kept developing the most annoying leaks (burping and farting noises non-stop). I threw it aside, and forgot about it for several weeks. Then, one day, I just decided to try it again.....and it worked AMAZING. Comfortable on my face, absolutely zero leaks, and no more waking up with deep lines. Since then, I have used it multiple different times (after changing my mask or cleaning my mask) and it's just like before. It either leaks like crazy, or works amazingly well. I cannot figure out what is causing this, and to the best that I can tell, it is exactly the same each time I put it on (no wrinkles, bunching of material, stretching too tight, etc...). Every time it seems like I put it on exactly the same, I align it exactly the same, I do everything exactly the same....and yet sometimes I get non-stop leaks....and sometimes I don't! Very frustrating! However, just because it works so well when it does work, I am not willing to throw out or give up. I just wish I could get more consistent results.

I had ordered a similar product that ended up not using because"¦. Even though it was a very soft material"¦. It didn't feel good after only a few short hours. This one feel soft and it didn't irritate me when wearing it. But it did prove to me that the sleep therapist was correct on the size I should be wearing. I stopped wearing my daughters mask cushion that was a small and went back to my medium one. So I immediately ordered the medium cover to help stop my leakage (which is why I was wearing my daughter's.

These little mask cushion covers are easy to use and really help extend the life of your CPAP or bipap mask cushion I will bee buying these again soon.

This sleeve or gasket is a little fiddly to use, but it does stop most of the air from blowing out of the mask into my eyes, so it's very good to have.