Oxford Aqua HB2 Hydration BladderKeeping properly hydrated while on the road is essential for your health and concentration levels. Oxford's top spec hydration bladder stows away neatly in the Aqua H2 compact waterproof backpack (sold separately). The bladder is suspended high in its own compartment to avoid contamination and to maintain an even centre of gravity. Features: Wide fill opening for quick, hassle free filling. Quick push and release tube connector for convenient storage.