Large capacity: 13L main compartment plus 1L auxiliary compartment plus 2*0.3L auxiliary compartment is equivalent to 18L bicycle backpack (with rain cover, key bag, removable bag and mesh pocket for bicycle helmet), suitable for outdoor driving activities such as cycling, camping, climbing and hiking. Breathability and comfort: adjustable strap and waist belt are suitable perfectly to each customer. The breathable back and hip belts are lined with mesh fabric for optimal comfort. The hip belt can relieve stress and ensure smooth and safe riding. Perfect irrigation system: The hidden outlet of the H2O humidification bag is installed on the shoulder strap. You can even drink water anytime while driving. The backpack is made of waterproof and durable polyester with a long service life. Reliable safety: Reflective strips on the seat belt ensure safety and worry-free driving at night. Ultra light and durable. Scope of delivery: upgraded outdoor backpack * 1 This 18 liter bicycle backpack is specially developed for cyclists and hikers. The ergonomic design makes the backpack more comfortable. Made of high quality and safe materials, strong and durable. It will definitely enhance your fantastic outdoor experience. It is very suitable for cycling, travel, vacation, hiking, school, camping, climbing, fishing, skiing and daily use. waterproof Removable mesh helmet bag In order to reduce the load, the designers used a durable waterproof nylon fabric wear and tear, more expensive and of better quality, to ensure durability and reduce the weight of the bag. waterproof The fabric is durable nylon abrasion, tear and water resistance, with good water resistance. If the backpack shakes, water droplets will naturally fall. Air transport The mesh belt and EVA foam are specially designed for shoulder straps, with a good breathability, light weight, breathability and thermal insulation, making it easy to use. Removable mesh helmet bag The high-density nylon elastic mesh bag is strong and durable, and the detachable design makes your journey more comfortable.