KUYOU Hydration Backpack: Crafted for Runners, Cyclists and Hikers Designed for outdoor enthusiasts, the KUYOU Hydration Backpack combines lightweight durability with burden-free carrying. The 2L large-capacity water bladder meets all-day hydration needs for sports, while the bite-valve suction design allows one-handed water replenishment anytime. Reflective strips and a built-in survival whistle offer dual protection, keeping you safe from dawn to dusk.Whether tackling mountain trails or trekking through forests, KUYOU is your reliable sports companion.