Easier breathing and body positioning with the ergonomically designed concave center and crescent cutout for your shoulders The side cutouts allow the mask to rest securely while in use minimizing interference on your face Choose your comfort with 2 adjustable sides and 4 different heights Keep cool and dry with the 3D air mesh side or turn it over and enjoy the plush, hypoallergenic pillowtop Add or remove foam layers to adjust to desired height level