Perfect for backpacking and hiking, the Gregory Bite Valve Cover keeps your hydration system protected, covered, and drip-free. This easy-to-use bite valve cover with integrated tether is compatible with the Gregory DryLock Magnetic Bite Valve (not included). Simply thread tether over hose before bite valve to secure cover. Fits up to a .5" or 13mm outer diameter hose. Manufacturer model #: 136978-5583. Keeps hydration system protected, covered, and drip-free Fits the Gregory DryLock Magnetic Bite Valve Perfect for backpacking and hiking Easy to install and use