PRODUCT DETAILS Replacing your bite valve from time to time helps maintain your hydration system. HydraPak&';s Bite Valve Sheaths provide a soft bite and are made of durable silicone. Perfect for chewers or to keep in your emergency gear kit with your bandaids and duct tape. Fits and replaces all HydraPak bite valves on our Reservoirs, SoftFlasks, and UltraFlasks. WEIGHT 5.7 g / 0.2 oz MATERIAL POM, Silicone