The Replacement SpringFit frame is a crucial component of ResMed's AirFit N30i and AirFit P30i CPAP masks, securing the cushion for a secure fit during therapy. Made from lightweight, flexible material, it adapts comfortably to facial features while allowing a clear line of sight for natural sleep. Regular replacement every 3-6 months, along with proper maintenance, ensures hygiene and longevity. Note that the frame isn't interchangeable between N30i and P30i masks due to differing sizes and shapes.