The F20 & F40 use a slightly different headset, The F40 was designed to be lower on the face.

Hello Joe, I have used the Resmed F20 Airtouch for over two years, it worked for me until I switched to the new F40 mask, this mask is super soft and pliable giving me a good seal. I have a well trimmed beard and this mask fits my face great. I find my breathing to be more consistent using the F40. ...

Hello Everyone, I recently had my first two-part sleep study at my local hospital. The results showed a fixed 8cm/hg was the best setting for my therapy. I question this because, according to OSCAR I have mostly central apneas and not obstructive. I also at times have cheyne-stokes-respiration. I th...