"Lightweight and breathable: This 15L bike backpack weighs only 500g (1.1lbs). The back and shoulder straps are equipped with a sponge ventilation system to generate airflow when worn. Breathable and durable, suitable for outdoor sports such as hiking, mountaineering, cycling, camping, skateboarding, running, fitness, etc. Comfortable and labor-saving: The adjustable, padded S-strap, shoulder straps and waist belt allow the force of the water bag to be scientifically dispersed and ensure a comfortable fit. The water bag pocket is connected, no more falling. Sufficient space and safe: This hydration backpack has 12 different pockets and 3 hanging systems to place mobile phones, water bottles, iPad snacks, gloves, flashlights and wallets. 8 night reflective strips and 1 life-saving whistle make travel safer. Waterproof and scratch-resistant fabric protects the interior of the backpack. Leak-proof liner: The high-quality 2L liner is made of EVA material, BPA-free, and FDA-approved. 6-inch water inlet for easy watering, ice laying and cleaning. Removable PE water pipe with drinking water switch, convenient for drinking and prevent leakage."