The Reservoir 3.0 is a 3 liter reservoir perfectly designed to pair with your ALPS pack. The Ultravalve on the Reservoir 3.0 features a revolutionary articulating bit valve as well as a built in check valve that eliminates backwash and prevents air from entering the tube. It also has a feature that allows it to twist open for a no bite, full flow function. The anit-microbial IonPure treatment helps prevent bacteria and mold growth. The Reservoir 3.0 also features Dual Cap technology, one cap is large for cleaning while the other cap is small and perfect for filling with liquid.