1. PREMIUM PEVA MATERIALThe water bag is made of PEVA material,more flexibility and abrasion resistance than other material.TPU drinking tube make the whole water bladder taste free. Perfect size is compatible with most sizes hydration backpacks. 2 liter capacity is almost fit for most sports. It conveniently quick and easy to have a drink. 2. Beautifully designed : For upgraded tightly sealed auto-lock socket, easy to connect or release.You can fill water even the hose is disconnected. The double sealing design for wide closure will effectively protect from leakage also be easy for cleaning and refilling. 3. FREE VALUABLE PACK SPACE LIGHTWEIGHTSince hydration bladder is stored in the backpacks , no extra space is used. Besides this. The big opening makes for easy filling / pouring of water. Also can put some big ice cubes into water bag to keep water cool. 4. EASY TO STAY HYDRATED : Because of the drinking tube attached to hydration bladders, remaining hydrated is now simple. Simply bite the mouthpiece to suck water. Soft mouthpiece with easily accessible ON/OFF valve prevents leakage. It also has a cover to keep dirt out. Conveniently control the water flow by biting, when not bite, the water will not leak out. 5.You can apply backpack hydration bladder for outdoor activities: hiking, running, bicycling, skiing, riding, camping, cycling, climbing, etc. It is a must have for sports enthusiast and an ideal gift choice.