<ul><li>Size: Medium</li><li>ComfortGel Blue Cushion and SST Flap for ComfortGel Nasal CPAP Masks Medium</li></ul><br><br>This is the replacement Medium size gel cushion and SST flap for use with ComfortGel Nasal CPAP Masks. There are four sizes available For the cushion: petite, small, medium, large. PLEASE NOTE: this cushion and flap are Medium size, but it fits the small and medium frame, so you may see S/M on the product.