Bite Valve Replacement Mouthpiece 90 Degree Silicone Hydration Pack Nozzle (4 Pack), Shutoff Valve, and O-Ring Kit for Outdoor Backpack Hydration Bladder Reservoir (Silver) HYDRATION BLADDER COMPATIBILITY - The bite valves are compatible with most common hydration bladders brands. BITE VALVES - are Self-Sealing, have a one-piece construction so there are no water drips. SOFT and Durable for faster flow from your water bladder. There are 4 (four) mouthpieces included in the package so you can use your backpack reservoir for an extended amount of time. MOUTHPIECE - ON/OFF Shut Off Valve allows you to easily control water flow with the yellow lever. Compatible with drinking tubes and bite valves of most hydration bladders. If you lost or broke yours, you no longer need to replace the entire bladder. Simple attach this nozzle to the drinking hose and mount the mouthpiece. O-RING - If your bladder was working fine and it now leaks where the tube connects to the bladder, the you probably lost the o-ring. Simply put this on and continue using the bladder. GUARANTEE - If you have any questions or issues with your bite valve, simply contact us within 30 days for a full refund.