Product details: Brand: ROCKBROS Product name: Multifunctional bicycle carrier bag Material: Bag body: Polyester+TPU/Buckle: Nylon+PA Product size: 30*15*60cm (unfolded form), 30*15*45cm (rolled form) Backpack capacity: 13.5 ~ 18L Product net weight: about 1004g Features: Multifunctional, practical design: The bicycle bag has hidden shoulder straps that can be removed by opening a zipper on the inside of the main compartment. This allows it to be transformed from a rear rack bag into a practical backpack - ideal for commuters and longer tours. Flexible, adjustable capacity: The bicycle bag offers a large volume of approx. 13.5-18L. Thanks to the roll-top design, the capacity can be adjusted as needed, while the integrated mesh bags allow for categorized storage - ideal for different packing requirements. Excellent waterproofness: The seamless welding technology and the fully sealed inner material make the bag waterproof, so your gear stays safe and dry even when riding in the rain. (Warning: too long exposure to the rain can also damage your bag, so you should be careful to protect the bag and not let it stay in the rain for a long time.) Practical details: With a helmet holder on the side, a chest strap that serves as a whistle, a reflective logo for better visibility and a holder for a rear light (not included), the bag is ideal for safe and comfortable rides. Easy and quick installation: Thanks to the adjustable buckles, the Sport Bag can be easily attached to a variety of luggage racks. The steps are intuitive: adjust the distance (10-20cm), fasten the buckles and fix the lower straps - ready for use in seconds.