Sizing Information: Four Solo nasal cushion sizes are available -- Small, Medium, Large & Wide -- to fit a wide range of users. All Solo masks use a single adjustable headgear size, so any cushion size will work with your Solo mask. If you would like to change the size of your mask, you can just purchase a different nasal cushion size and adjust your headgear accordingly. Check the side of the cushion for the embossed letters S, M, L or W.