One-size-fits-all this day pack is a perfect size for men and women justable chest and shoulder straps fits chest sizes 22-50 in the adjustable waist straps fit waist sizes 22-50 in main compartment is ideal for placing larger items the Front Bottom Park pocket has many utility pockets as well as zippered mesh pocket to place many of your smaller items also the backpack has a filter lined media pocket for placing your phone or glasses the two concealed side pockets are perfect for storing items such as your phone wallet and passport the rear compartment hose the hydration bladder backpack measures 18 x 10 x 6 in and weighs 40 oz made from water-resistant 600D polyester material. Backpack has breathable mesh padding on the back side comfortable shoulder padding backpack is perfect for hiking biking cycling and walking.