Introducing the Big Zip™ EVO—the latest evolution in taste-free hydration. Delivering an extremely high flow rate, self-sealing HyFLO™ bite valve, large drink tube, simple one-handed filling, easy cleaning, fast drying, quick access drink tube disconnects, leak-proof shutoff valve, and more, the Big Zip EVO is a top pick for hikers, backpackers, travelers and mountain bikers. The Big Zip EVO is available in 1.5L, 2.0L, 3.0L & Lumbar 2.0L.