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 night’s sleep, confident that their seal is safe.