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I went in for a mask fitting a while ago and decided to give the AirFit F40 a try. I had been using the F20.

I was having terrible results so I ordered some compatible mask liners from RemZzzs. Tried it for the first time last night and still woke up to a red frowny face on my display.

Here is my sleephq link: https://sleephq.com/public/teams/share_ ... /dashboard

I'd appreciate any insight.

Thank you.

Either the sizing is wrong or the fitting is wrong or this mask is simply not suitable for your facial structure.

Mike20878 wrote: ↑

Fri Oct 17, 2025 8:39 am

give the AirFit F40 a try

Paste this in the YouTube search bar ---> fitting and adjusting airfit f40 mask

Watch a few videos - some are better than others.

I think the sleep tech did me wrong. He insisted I was a large, but I just tried using the size guide and it looks more like I'm a medium.

My nose is completely out of the box lengthwise on the L/SW boxes.

I had a good night last night, actually, but woke up at one point with pain in my nostrils again. I must have had it too tight.

I'm going to talk to them about correcting the sizing.

I've experimented with the F40 for a while.

I would sometimes experience pain at the columella (area between the nostrils). Sometimes it was because it was too tight. If that wasn't the case and I still experienced pain, a pea of lanolin cream solved it.

Ultimately, I found that my mouth was falling open with this mask, causing leaks. The solution would have been to use mouth tape or a chin strap or both. I ultimately decided to both tape and strap and go with the P10 (nasal pillows). I didn't see a point of taping and strapping with a full face mask.

I went back to my F20 for a few days while I waited for the medium F40 to arrive.

At first I was still having leaks, but I saw a video that mentioned routing the hose up above your head. I hadn't thought that allowing the hose to hang over the side of the bed could make much of a difference, but it did.

I routed the hose above my headboard and had great results.

The new medium F40 came on Saturday and I decided to try it without a mask liner to see how it went. Not very well.

Last night I used the liner and didn't experience many leaks, from what I could tell.

Thursday on the F20: 2.4L/min; Friday 16.8L/min. Saturday with the F40, no liner, 56.4L/min, and last night F40 with liner, 34.8L.

I'm surprised my doctor never asked how I'm routing the hose. He originally had me switch to a full face mask from the F30 so I'm not sure how much different the F40 would be in terms of style of mask.

Hi. I been using the f40 for about 1 1/2 years now. I have good nights and bad nights when i leak alot to not at all. It varies from night to night. But for me it works best if my face is clean and i havent used any creams, lotions or potions on my face prior to put the mask on.

I've found the F40 not so good at handling high pressure. I got farty leaks at 15cmH2O. The weak spot (for me) seems to be between upper lip and nostrils, despite cleaning cushion and face thoroughly. I resolved this by applying silicone tape strips to my face where it leaks. That provided a great seal and for the past 2 weeks, minimal leakage and certainly not the farty ones that wake you up.
I use the 'siltape' brand. It's reusable for several nights and doesn't hurt on removal.