The benefits of hydration packs are clear. They are convenient, efficient and assist ongoing performance. The Camelbak Hi Viz is used around the globe from Australia to the Panama Canal, whenever visibility is imperative. Lightweight, durable 500D High Density Nylon Fabric Three-point tear-away harness prevents accidents 3.5L dual-zippered front pocket with internal organizer for easy access to gear Integrated cover keeps fill port clean and protected Convenient filling with external access to the reservoir fill port Reflective strips on pack and harness stand out day or night Closed cell insulation keeps water cool for hours ANTIDOTE™reservoir’s ultra-wide 88mm opening for easy cleaning and ice addition Quick Link™ Modular tube connections with positive shut-offHydroLock™ and exit port auto-shutoff PureFlow™ tube keeps water tasting fresh from the first use and beyond Bite Valve Cover keeps Bite Valve clean from dirt and debris Big Bite™ Valve made of self-sealing silicone HydroGuard™Embedded compound technology inhibits the growth of bacteria on the reservoir and drink tube surfaces. Does not protect the user from bacteria or other disease causing organisms.