If you're the type of the person who calculates combined weight and cuts off tags to save half an ounceOK, that's a bit extremethen CamelBak's Arete 18 Hydration Backpack may be the solution for you. Tipping the scale at a whopping ten ounces, this slim pack will fit in perfectly with your lightweight obsession. Use it as a reservoir sleeve for CamelBak's already lightweight two liter Antidote reservoir or stuff in your own summit essentials. Either way, the Arete's DWR and PU coated 70D diamond box nylon construction will protect your gear from wind and rain without weighing you down. In fact, when the 975 cubic inches of compartment space is largely unoccupied, tighten down the two compression straps for a denser and less bulky pack. From extra water to sunglasses and snacks, the Arete may be light, but its sure got your back when it comes to carrying trail essentials. Seasonafter season, CamelBak's super scientists have been hard at work refining andperfecting the Antidote reservoir, the industry's most popular solution tohydration. At the turn of a cap a quarter turn to be exact, you can open orclose the reservoir, refilling and securing it again in seconds. Centerbaffling and a sleek design prevent your water from jostling about inside yourpack while running, hiking, or hitting the park. When not off exploring theworld, simply disconnect the tube using the Quick Link System and hang up theAntidote for proper drying or storage. Since last year, CamelBak's go toreservoir system has actually lost some weight, reducing bulk in the fill portand offering you that much more convenience.