Camelbak Maximum Gear ThermoBak 3L/100 oz. ACU Camouflage Backpack-style Hydration System Camelbak Maximum Gear ThermoBak 3L/100 oz. ACU Camouflage Backpack-style Hydration System Sternum strap for added stability Exterior fillport with ergonomic handle for filling on the go This system has proven itself with every branch of the US Military.