Applicable gender: neutral / both sexes Cover opening mode: zipper Lining texture: Nylon Capacity: 20-35l Size: l (41cm * 31cm * 18cm), s (39cm * 29cm * 16cm) Color: sapphire blue, blue, rose red Functions: breathable, waterproof, wear-resistant, anti-seismic, load reducing Style: British style Bag internal structure: zipper bag, mobile phone bag, certificate bag, sandwich zipper bag, computer bag, camera bag Number of shoulder straps: Double Lightweight body, long back is not tired: light nylon fabric, wear-resistant and durable Healthy spine protection, comfortable and breathable: comfortable and breathable back cushion, reasonable and uniform stress S-shaped fitting back: S-shaped fitting shoulder strap is close to the shoulder, increasing the contact surface, easy decompression S-shaped widened shoulder strap: the first layer, breathable high sponge pad; The second layer, shoulder belt widening buffer design; The third floor, decompression and load reduction seismic design Reflective material, safe travel: the bag is equipped with reflective strip, which can effectively reflect light at night Large space, easy storage, book water cup fully installed Waterproof fabric: waterproof, effective protection of textbooks