ERGONOMIC AND CONTOURED DESIGN: The Hiking Backpack Water Bladder Vest Kit targets your back while gently protecting your muscles. The ventilated mesh keeps air circulating, preventing discomfort from accumulated heat, providing superior air circulation and breathability to keep your back cool. PREMIUM QUALITY WATER BLADDER: The 1.5-liter food-grade water bladder is made of PEVA, which is non-toxic and odorless. It can be filled with water and ice super fast. At the same time, it's more convenient to clean. The water tube (40 length, 0.4 diameter) provides a healthy flow for easy drinking. The water temperature range is -20~+50. PERFECT COMBINATION: Our running backpack measures H 14.5 x L 7 x W 0.07 inches and weighs 0.18 kg (0.2 lbs). This lightweight cycling backpack features adjustable hip belts and shoulder straps that can be modified to fit your torso. It includes a 1.5-liter hydration bladder. The perfect size offers a good balance between reasonable weight and bulk while providing a sufficient amount of water, suitable for men, women, and youth. Safety & Multiple Storage Options: Reflective trim for night safety and strap clips to keep extra straps secure. Additionally, there are two large and two small pockets on the front of the bag. You can put some gel/soft candy/paper towel/towel/mobile phone/key or other items in the front pocket. Sweat can be avoided for quick and easy access. COMPREHENSIVE APPLICATIONS: This hydration pack is specifically designed for road cycling, running, hiking. Its compact structure and small size make your back light and stable, without causing much wind resistance. It's the perfect choice for men, women, and children. It doesn't move or bounce around. Ideal for cycling, hiking, running, skiing, biking, climbing, hunting, racing, and training. A great gift for friends and family who enjoy outdoor sports.