1/4 turn - easy open/close cap, lightweight fillport, dryer arms, center baffling and low-profile design, patented Big Bite Valve, HydroGuard technology, PureFlow tube, easy-to-clean wide-mouth opening. Bike tool organizer pocket, reflectivity, safety flasher loop, sternum strap whistle. Snack, sunscreen, phone, cash, keys. CamelBak Got Your Bak Guarantee: If they built it, they'll Bak it with their lifetime guarantee.