Package includes: 4replacement bite valve included in the package, so you can use your backpack reservoir for a longer period of time. Bite valve are self-sealing, have one-piece construction so there are no water droplets. Soft and durable for faster flow from your water bladder. 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 lose or break yours, no need to replace the whole bladder. Simply attach this mouthpiece to the drinking tube and mount the mouthpiece. Connection to water pipe outer diameter is approximately 8.5 mm. Suitable for normal water pipe of 7.5-8.5 mm inner diameter. The bite valves are suitable for all brands of hydration bladders.