Gramps, thanks for your post. I started my journey 1/6/21. I went to pick up my equipment and they started me out with the F20, medium. After about 10 days and much frustration from nonstop leakage, I went back to my home care store. The tech went through all the various masks available, asked questions on my sleeping habits, etc. great tech! My main issue with the 20, besides being too large was feeling claustrophobic. He felt the F30i, small would work best. I’ve been using this new mask and prefer it much more than the 20. It has a good fit, I really like the top hose fitting that moves with me. It’s just taking time to get adjusted to falling asleep with it on. I’m contemplating a CPAP pillow as I’m a side and back sleeper. I feel this mask isn’t very comfy sleeping on my side. I’ll get there but it’ll take time.