resmed airfit f20 replacement cpap mask headgear (large) resmed headgear size large. this is the replacement headgear for the resmed airfit f20 full face mask and f20 for her. the innovative headgear is designed for extra softness and stability, the plush straps helps ensure patients settle into therapy quickly and comfortably. the resmed airfit f20 full face mask is compatible with three different headgear sizes: small, standard, and large, to ensure an optimal fit for the user. includes: 1 headgear in selected size or color 1 set of magnetic headgear clips