【Waterproof Material & Insulated Lining】 The bike rear rack bag is made of water-resistant fabric with protective padding that provide a cushion to reduce shock when riding on road. Insulated lining keeps your beverage and food cold or warm for hours. 【8L Large Capacity】14.9 x 6.3 x 6.2inch. The bike trunk bag includes a spacious main compartment, a top pouch, a side pocket and inner mesh pocket, which help to keep your essentials well organized. It’s quite convenient for long-distance riding. 【Easy Tool Free Installation】2 adjustable Velcro straps and 2 fixed buckles ensure stability, also make it easy to be installed and unloaded in seconds. This Bag fit most of road or mountain bikes' racks. 【Safety Design】This bicycle rear seat bag is designed with two side reflective logos, all-around reflective pipeline and back reflective strip with taillight loop (not included taillight), which provide bikers a safer night riding. 【Multifunctional Use】It can be a bike rear rack Luggage bag, a shopping bag and shoulder bag with an removable, adjustable shoulder strap. After parking the bike, you can take this trunk bag with you and don't worry about it being stolen.