PLEASE NOTE THE DIFFEREnt SKU # - F&P HAS CHANGED THE SKU # Replacement silicone seal (also called a silicone cushion) for the F&P Simplus full face CPAP mask. REF: 400HC581 (Large). The F&P Simplus Seal uses F&P's RollFit design to automatically adjust and optimize the seal of the mask. The one-piece seal rolls back and forth on the bridge of the nose. This automatic adjustment minimizes pressure on the nose bridge and creates and effective and comfortable seal throughout the night, even during movement.