This is the replacement silicone cushion for both the ResMed Quattro FX Full Face CPAP Mask with Headgear and ResMed Quattro FX Full Face CPAP Mask for Her with Headgear. Dual-Wall, Spring Air Cushion - High-tech Spring Air cushion distributes pressure evenly and absorbs even the slightest user movements, so users can enjoy a good nights sleep, confident that their seal is safe. About Cushion Sizes: Both the frame and cushion of the Quattro FX are sized. The cushion size must be the same size as the frame to function. Sizes cannot be mixed. For example: Small cushions fit only small masksMedium cushions fit only medium masksLarge cushions fit only large masks ©ResMed 2010 Used with Permission to all WebPages with ResMed picturesRESMED Minimum Internet Retail Price & POLICIES FOR THIS PRODUCT - We are only authorized to sell and ship Resmed products to end-users residing in the United States. A prescription is required for the purchase of certain products on this site including masks, humidifiers, and machines. Prescriptions can be emailed to email@example.com or faxed to 856-767-7151. All services are provided solely by The CPAP Shop and independently of the manufacturer. These services include the advertisement, ordering, sale, delivery, instruction, and setup of the products.