Introducing the Big Zip EVO-the latest evolution in taste-free hydration. The Big Zip EVO delivers a significantly higher flow rate than previous Platypus reservoirs and a host of features, making it a great option for backpackers, hikers, and mountain bikers. FeaturesSlides both directions to easily open, securely close and fill reservoir.Allows for easy one-handed filling.Instantly stops flow and offers reliable stowing.Offers fast, easy access-no more digging down in your pack.Offers low-profile support and makes for easy cleaning and drying.Improves flow along with, larger 5/16" drink tube.Embedded Silver-ion protects clean water from mold & bacteria.All materials are certified taste-free, BPA-free, BPS-free, and phthalate-free.