【Ergonomic and Comfortable Design】: The backpack is made of 3D polyester mesh, which maintains air circulation, keeps your back cooler, prevents heat buildup and discomfort, and provides good air circulation. The chest strap can be adjusted as desired. 【Lightweight Design】: This multifunctional hiking backpack/vest is made of high-quality nylon material with a soft wool wrap to reduce friction against the body. It weighs approximately 140 grams and holds up to 5 liters. The chest has a pocket for a soft water bottle and a hydration bladder where you can secure enough water during outdoor exercises. Multiple Pockets and Reflective Stripes: The backpack features a reflective stripe design that serves as a warning at night during exercise with a light source to ensure your safety. The main compartment with double pockets is suitable for hydration bladders, light clothing, and more. In the front pocket and conversation compartment, you can store a 500 ml soft water bottle or energy supplements, while the zippered bag can hold a 6.6-inch phone, allowing you to listen to music and jog at the same time. 【Wide Application】: This outdoor backpack has a neutral design for both men and women, is very suitable for both men and women, has reinforced and stable shoulder straps, a compact structure, small size, wind resistance, and is easy to carry. Perfect for cycling, hiking, camping, travel, trekking, mountaineering, racing, training, and many other outdoor sports.