[Prevent Air Leakage] The perfectly fit size further avoids air leakage, and the connection is tight to prevent falling. [No Noise] There is no noise disturbing sleep no matter when plugging into head frame or into the hose or during use at night. [Perfectly Adapted size] Diameter and size are fully compatible with Dreamwear. [Elbow With Swivel] Quick-release elbow that reduces tugging along the mask. [Tubing Quick Release] The mask can be quickly disconnected from the tube, which is convenient for working without removing the mask.