This reservoir with Thermal Control insulation turns any pack into an all-season 3L hydration system. DESIGNED TO CARRY: Water ANTIDOTE RESERVOIR FEATURES:Quick Link System, 1/4 turn - easy open/close cap, lightweight fillport, dryer arms, center baffling and low-profile design, patented Big Bite Valve, HydroGuard technology, insulated PureFlow tube, easy-to-clean wide-mouth opening, 100% Free of BPA and BPS CamelBak Got Your Bak Guarantee: If we built it, we'll Bak it with our lifetime guarantee.