USB charging: External USB charging interface, built-in mobile power connector, hands free, charging while walking, little innovations are great and convenient. You can charge the mobile power adapter directly through this small connector without that remove mobile power supply. The hidden interface can prevent rain from washing itself and the lifespan is longer. Waterproof: The material consists of scratch-resistant, wear-resistant and water-repellent materials and is extremely tear-resistant. Ergonomic design: S-shaped shoulder strap, ergonomic design, breathable shoulder strap, elastic decompression, comfortable and easy to carry, breathable decompression. With this design, if the backpack is heavy, it can take the total weight distribute effectively and relieve the shoulders. Large capacity: Humanized space that offers space for daily needs and allows you to travel comfortably Usage: Suitable for any occasion including school, travel, hiking, conference, work, etc. Size: width 34 * height 44 * thickness 13 cm