100% WATERPROOF: Made of 840D nylon and 0.1mm TPU, this ROCKBROS rear bag is completely waterproof, durable, and tear-resistant. This bag can also perfectly protect your belongings in heavy rain. Furthermore, this bag is easy to clean. LARGE CAPACITY: approx. 182146*cm; Weight: approx. 900g. The capacity of the rear bag is 20-27L. Thanks to the roll top, you can store t-shirts, pants, jackets, shoes, tools, etc. Perfect for a long bike trip. ADJUSTABLE BUCKLE: This waterproof trunk bag uses a new adjustable buckle to mount it to various luggage racks. With two hooks, you can adjust the top buckle to the appropriate length. The fixed device on the bottom can be rotated 360° and smoothly moved left or right according to your needs. DETAILS: The exterior of the bag features a mesh pocket for easy access to frequently used items, such as a raincoat. The main bag also has internal pockets for convenient storage. The back of the bag features a hard-shell front panel to protect the bag from wear and tear. A reflective logo adds safety in the dark.