Vitera Mask Seal (Medium) Medium (Pack of 1) auspowers_batchsix The MHX HS is a 26 Thread length 11mm The MHX HS is a transducer mounting hardware kit for XHS model transducers will not cause pressure on the head Lightweight Adjustable Headband Lightweight headset for all day comfortAdjustable headband will fit for large or small head Soft T pad Soft T pad make sure the headset perfectly stand on the headEasily pick off the headset from your head Quick Disconnect More convenient on wearing the RollFit XT Seal rolls back and forth on the nose Fisher & Paykel's RollFit XT Full Face Seal is designed for use with all F&P Vitera CPAP Masks