The AirFit replacement cushion is designed to fit the AirFit F20 mask by ResMed. The F20 nasal mask is similar to the F10 version, but has additional padding for increased wearability. Therefore, the replacement cushion is compatible accross all models. It is also compatible with the "For Her" models of those masks. Sleep Apnea Solutions offers the Resmed F20 Replacement Cushion in 4 different sizes (XS, SM, MED, LG).