Park Hydro fits comfortably in your hand, with a stretch carrying system and 500ml flask that compresses as you drink. Small external pocket fits a car key, mobile phone, MP3 player, or gels. One size fits all. 1 mobile pocket. 1 key holder. 1 trash pocket. Pvc, Phthalate, bisphenol-a free. Blaster valve. Soft flask included 1(500ml - 18oz).