Large Reflective Area --- Unique designed large area reflective fabric to increase visibility at night, together with the rear loop for taillight(not included), bike rack bag ensues bikers a safer night riding. Rainproof & Built to Last --- The bike trunk pack is made of 600D Oxford fabric coated with superior PU film, which is rainproof and easy to clean. The laminated waterproof zipper also help to prevent rain from penetrating in. Exquisite workmanship, durable and firm, provide a long service life. 8L Large Capacity & Great Organizer --- Dimension of 15 x 6.3 x 6.3inch (L x W x H), large enough to store wallet, phones, towels, clothes, bike tools, water bottles, maps, food, etc. This under seat storage bag includes a main compartment, 2 side pocket, a top zip pouch and 2 inner mesh pocket, help to get your essentials well organized. Also A Chest Bag --- Not only can be used as bike bag, but also it is a stylish commuter chest bag when taking out the hidden shoulder strap from the bottom pocket and get it hooked in other end loop. Moreover, it come with a comfortable handle to make it a handbag. Easy to take it away anytime when finish your riding. Tool Free Installation --- This bicycle rear seat bag come with 4 adjustable hook and loop fastener straps, make it easy to be installed and unloaded in seconds, suitable for most bicycle racks, such as mountain bike, road bike, electric bikes.