31 shoulder drop Product dimensions:20.1×12.6×7.1 inches(51x32x18 cm).Fabric: Water-resistant Polyester. SBS Zipper and YKK Buckle The backpack includes an adjustable hip belt on this bag that fits waist sizes 31?C55 inches(the belly strap is not removable).With padded shoulder straps and a chest strap to distribute weight, the pack is easy to wear. There??s always a chance you??ll find yourself off the beaten path. There is a waterproof cover in its own zippered compartment at the bottom of the pack,while an integrated raincover offers protection from sudden downpours. The main compartment has an array of internal dividers including a space suitable for holding a hydration bladder and tube,big enough for a 3 liters hydration bladder or a 15.6laptop.one compartments keep you organized on the go, while still leaving plenty of extra space for your other necessities. Overnight packs:An overnight pack is identifiable by the tall and thin design. Most of these small hiking backpacks offer between 20 and 40 liters of capacity. This type of pack will work as a hiking pack for a day trip too.You could use the bottom straps, and secure the sleeping bag to the outside.