The ingenious design of the top opening Slide-Seal™ makes filling, emptying, and cleaning the Osprey Hydraulics Lumbar 1.5L Reservoir easy after use. The two circular compartments ensure optimal stability, a slim profile, and limit liquid movement on difficult terrain. The magnetic hydration valve is convenient to handle, even on the move, and can be secured with an intuitive locking system when not in use. Additionally, the hydraulic reservoirs are made from lightweight and durable thermoplastic polyurethane, free of PVC and BPA, ensuring unparalleled durability even in extreme conditions.