Features ‧ Unique patented hand-push shoulder adjustment buckle, allowing users to easily adjust the length of the shoulder strap according to the length of the back ‧ Ultra-light aluminum alloy built-in back frame can fit the curvature of the back, so that the weight is evenly distributed to the shoulders and waist ‧ Breathable three-layer mesh cushion ‧ Equipped with bellows bag with expandable capacity and side pockets on both sides ‧ The upper and lower spaces are separated, and the lower compartment can be opened independently ‧ Equipped with rain cover system and water bag water pipe outlet