The 2L hydration bladder is made of durable and safe TPU material. It fits perfectly in your hydration compatible Wanaka Backpack. It hangs from the provided hanging loop, fits in the built-in hydration compartment, and the tube routes through the included hydration port of your pack. It includes a locking bite valve so you don't get water where you don't want it. 

It is BPA free and approved by the FDA, EZ-71, and LFGB.