Fisher & Paykel's RollFit Nasal Seal is designed for use with all F&P Eson CPAP/BiPAP Masks. As the name suggests, the one-piece RollFit Seal rolls back and forth on the nose, auto-adjusting during sleep to reduce pressure on hard to fit areas, like the bridge of the nose, while increasing overall seal and comfort. Three sizes are available -- Small, Medium & Large.