OutdoorMaster Hydration Bladder with Leak Proof Connection System with 2.5L/3L Capacity (3L) The OutdoorMaster Promise: 100% Satisfaction Guarantee. HYDRATION BACKPACK - OutdoorMaster Hydration Backpack is a backpack with built-in 2.5L (85oz) water bladder. ODORLESS MATERIAL - Made of odorless material for fresh water without any plastic taste. Easy to clean. WATERPROOF COVER INCLUDED - A waterproof cover is included so that you can keep your gear dry in rainy weather. What You Get: OutdoorMaster Hydration Backpack 2.5L, our customer-favorite 6-month warranty and friendly customer service.