2 Pack Hydration Backpack Pack with 2L Hydration Bladder, TNYSPORT Lightweight Breathable Water Backpack with 3 Layer Pockets, Reinforced Shoulder Straps2L(70 oz) Hydration Bladder Bag: This water backpack passed the pneumatic pressure 24 hour swing test and 24 hour vibration test. Fully pressure and leakproof for carefree cycling, running, hiking, and other outdoor adventures. Made of EVA material, 100% odorless, tasteless. High Quality and Comfortable Material: The hydration Backpack is made of high grade nylon waterproof material, light, wearable, and comfortable, a breathable mesh back to prevent