I'm using the Mimi-G oattern. The adult female size fits me and DH. I've used 2 layers of tightly woven cotton. I added a bias channel across the nose, into which I push a pipe cleaner, doubled & twisted, which makes it possible to get a good seal to the nose bridge. I tried adding a layer of non- woven fabric as an extra layer inside on one mask, wore it shopping yesterday and found I couldn't breathe!