The ResMed AirFit N30i nasal cushion is the silicone seal that attaches to the AirFit N30i nasal CPAP mask frame, forming the contact point between the mask and the face during therapy. Over time, natural facial oil build-up breaks down the silicone consistency, reducing seal integrity and leading to mask leakage. When leaks increase or the cushion shows visible wear, it is time to replace it. Each cushion size is colour-coded for easy identification and reordering: small features a red dot, medium is blue, small wide is purple and wide is grey. All four sizes fit the same AirFit N30i frame. Sold as cushion only — diffuser filter not included.