Designed for trail-to-town versatility. The Arete(TM) 18 is perfect for a quick hike. Carry your fuel, extra layers, and 1.5 liters of water in the Crux(TM) reservoir. Secure your fit with an adjustable sternum strap, stow extra goods in stretchy side pockets, and keep the essentials secure in an interior zip pocket. When not needed as a daypack, the Arete(TM) 18 converts into a reservoir sleeve, perfect for holding your water supply steady inside a larger pack. Finally, its&'; ultra-lightweight design packs down to fit inside luggage for lengthy travel. How&';s that for double-duty? 2 in 1 Design: Converts from pack into reservoir sleeve. Ultra Light Materials : Less bulk, perfect travel day pack. Cargo Compression: Keep gear close to your body for better balance and increased stability. Essentials Org Pocket: Keeps your small essentials organized and secure. Removeable Sternum Strap: Offers a range of adjustments for a custom fit and increased stability.