Pipe with whistle is perfect for fans of free diving. Whistle at the bottom of the pipe is used for signaling in case of emergency. ULTRA DRY system provides supply airinto the mouth without simultaneous diver scooping water. Pipe has a special compartment in the upper part, which prevents water from falling into the breathing hole.If still a small amount of water spilled below the bottom of the tube is a valve that drain it outside without allowing access to the mouth. Pipe has a corrugated PVCconnector and a comfortable and convenient mouthpiece made from the highest quality non-allergic materials.