HydraPak Comet Bite Valve - New, lightweight valve self seals after each sip and can be opened and locked with one hand to prevent leaks when not in use. A dust cover protects the silicone valve from outside elements. Features High-flow valve delivers water when you need it most. Self-seals after each sip and can be open and closed during activity with one hand. Dust Cover protects silicone bite valve from collecting dirt Universal 1/4 diameter fitting Safe & Reliable 100% BPA and PVC Free