Alrimaya Hydration Pack Backpack for trips and hiking. Type: Portable water bladder (tactical water bag). Capacity: 2.5 liters. Materials: Made of durable fabric (nylon or polyester) resistant to external conditions, and includes an internal bladder for storing liquids with a drinking hose to facilitate drinking water while walking or cycling. Color: Sand/Khaki. Features: Lightweight, with adjustable shoulder straps, and a large external filling opening for easy filling.