1. Large capacity and quality materials: The bicycle backpack has a capacity of 18 litres and has two zip pockets on both sides of the straps for keys and wallet. The side mesh pockets can hold water bottles, and there are also two compartments for better organisation of what you take with you on your journey. The waterproof backpack is made of abrasionresistant and waterrepellent material and is therefore extremely durable and waterproof. 2. Ideal heat insulation and drinking system: Our bicycle backpack has a thermal compartment made of waterproof, dirtrepellent material, which is easy to clean, without having to worry about it leaking. The Velcro fastener in the compartment keeps the hydration backpack in place and there is a hidden drinking opening on the shoulder strap, so you can always drink a sip of water, whether you are cycling or hiking outdoors (2 litre drinking bag not included). 3. design and multifunctional: The backpack has a helmet cover and a carabiner on the to keep your helmet safe. The backpack is equipped with a whistle that you can blow to get help if you have problems outdoors. The reflective strips on the outside of the ultralight MTB backpack make it safer for you to drive or run at night. The hiking backpack has two elastic sides for hanging trekking poles. 4. Lightweight and adjustable and ergonomics: Our sports backpack is designed to be lightweight and made of lightweight fabrics that can reduce strain when you go to use them. The shoulder straps of the backpack can also be adapted to the different body types of men and women. The back of the backpack is made of breathable mesh fabric, which makes it comfortable to carry without being stuffy.