LARGE OPENING:Different from others,our has one of the largest opening.The big opening is easy for pouring water and it is wide enough for a hand or bottle brush easily access to the interior hydration bladder.You can even scoop ice cubes directly from the fridge into the water bladder,and best of all it has insulation that allows the water to resist quick temperature change. . HIGH QUALITY:The is made of premium material.Taste free, BPA free and 100% food grade.It wont leave a bad taste in your drink.The is also passed the pressure test,it is leak proof.Double sealing side technique has greatly improved durability. . REMAIN HYDRATED:The 2L water reservoir can withstand temperatures from -20 to 50 degrees.INSULATED TUBE resists temperature changes in hot and cold weathers.is compatible with Acsergery most hydration packs.It also comes with Acsergery drinking tube clips,the clips slide onto your shoulder straps and hold the drinking tube in place the clips prevent the drinking tube from dangling out in front of you. Enjoy sports with Acsergery it. . LEAK PROOF:Soft yet durable mouthpiece with Acsergery easily accessible ON/OFF valve prevents leakage.You can control the water flow by biting, when not bite, the water will not leak out. Quick-release tube is detachable. Auto shut off while the tube is removed, bladder will stay filled non-leaking.The dust cover will protect mouthpiece clean. . 100% SATISFIED SHOPPING:Once you placed your order,you will get a 100% REFUND PROMISE.If you are not absolutely happy with Acsergery your purchase for any reason, simply send it back for a full refund or to get a new replacement. No questions asked .