Nylon Backpack with Flap Buckle Fastening: Tourbon bike backpack bag is made from nylon and leather, and good stitching allows them to support the weight of your items well, and will not lose luggage while riding. Flap design to help keep out some rain or dust and keep stuff dry and clean Easy to Install: This bicycle rear rack bag comes with 2 hooks to attach to your rear rack, hooks can be hidden under a flop when not used on the bike 15L Large Capacity & Great Organizer: Dimension of 11.41 x 4.92 x 16.53inch (L x W x H), large enough to store laptop, wallet, phones, towels, clothes, bike tools, water bottles, maps, food, etc. This bike back seat bag includes a main compartment, an inner laptop sleeve and top zip pouch, an outside front zipper pocket, and 2 side pockets, which help to get your essentials well organized Safe Night Riding: The reflective strips on the water bottle pocket and shoulder strap help ensure safe riding at night, and the front leather slot can hold a tail light for enhanced visibility and protection Portable Design: The bike bag comes with a top hand strap and adjustable shoulder straps, making it easy to carry when you are not riding your bike. Converts quickly and easily from a bike bag to a backpack Tourbon bike backpack bag is made from nylon and leather, and good stitching allows them to support the weight of your items well, and will not lose luggage while riding. Flap design to help keep out some rain or dust and keep stuff dry and clean.