1. : The material of the bicycle frame bag is carbon fiber grain leather, excellent texture and stylish appearance. The surface and inside are coated with a special waterproof TPU coating. Builtin PP board. This water resistance bag protects stored items and does not deform them. 2. Easy installation and disassembly: Bicycle tube bag can be easily attached under the bicycle tube with adjustable Velcro fastener. The Velcro fastener is made of nonslip, soft leather to reduce friction on the bicycle inner tube. 3. Optimal storage space for small items: For most important items such as smartphones, wallets, keys, small bicycle pumps, cable locks, repair tools, etc. The main compartment is: size M 9.3 inches x 2.6 inches x 4.1 inches; size S 8.5 inches x 2.2 inches x 3.3 inches. 4. EASY OPEN DESIGN: Bike bag with large zipper for easy access, convenient for storing and picking things up.