Built to handle heavy loads with the creature comforts, the updated REI Mars handles extended backpacking in any season. Enjoy dual access to pack via the top-loading opening and the horseshoe-shaped, zippered front panel opening, which works much like a duffel opening. With a rip-and-stick torso adjustment, shoulder strap system easily slides along packs frame to fit torsos of varying lengths. Removable top lid pocket with water repellent zipper lets you stash your essentials to bring into tent, so pack can stay outside or in vestibule. Zippered pocket under lid stores maps and keys, spare batteries and other small essentials. Front panel features a welded, water-repellent zippered pocket for storing often-used gear. Precurved shoulder straps match your anatomy for nonbinding comfort on and off the trail. Dual-density foam padded backpanel provides a comfortable and supportive fit when carrying heavy loads. Precurved hipbelt is designed to cradle hip bones for a natural fit and to distribute weight without sagging. Hipbelt webbing system allows you to use a natural forward pulling motion for quick, easy cinching and precise adjustment. Internal sleeping-bag compartment is created by a zippered divider, separating it from gear and clothes in the main compartment. Utilizing four buckles, the packs streamlined compression system lets you cinch and strap down loads for jostle-free carrying. Concave head pod at the top of pack gives your head freedom of movement-no more staring at the ground. Two side pockets-one zip and one mesh-hold water bottles, energy bars and other essentials you want close at hand. Side hipbelt pocket stores those small essentials you want at your finger tips, such as lip balm and sunscreen. Lash points on the other side of hipbelt let you attach camera and GPS pouches. Lash straps on bottom of pack let you attach sleeping pad.