Features: Dual zipper design, high hardness, anti-rust and fading. 20-35L large capacity main pocket, multilayer storage space. Superior oxford cloth, waterproof, wear-resistant, breathable. Back invisible pocket and password lock dual anti-theft design. External USB port, reduce the charge limit of space, free hands. Included raincover, multiple protection, waterproof dampproof. S-shape widen shoulder straps, adjustable length and release pressure. Three-dimensional breathable pressure relief load, high elasticity.