Applicable gender: neutral / both sexes Cover opening mode: zipper Lining texture: Polyester Capacity: 20-35l Size: l (42cm * 30cm * 15cm), s (39cm * 28cm * 14cm) Color: sapphire blue, black, red Functions: breathable, waterproof, wear-resistant, anti-seismic, load reducing Style: European and American style Internal structure: zipper bag, sandwich zipper bag Number of shoulder straps: Double Easy load reduction chest buckle, multi-point support, balanced weight, scientific spine protection: Design shoulder width, breathable shoulder strap, adjustable fastener, three-dimensional soft back cushion, cushion and protect the caudal vertebrae Load reduction core design, ergonomic design, balance back force Waterproof, antifouling, protection: fabric surface water repellent treatment, waterproof, wipe dry Easy to put into the desk, no deformation, multiple lines of defense, stronger load bearing: easy to load children's school supplies, durable High density fabric, scratch resistant and wear resistant Large space, easy storage, book water cup fully installed Smooth hardware pull head, durable, smooth, no caliper Multi angle highlight reflective strip to protect children's safety at night There is a water cup pocket on each side of the bag