The Twins Convertible Backpack is made of durable nylon material, with heavy duty buckles and zippers. All of the stitching is strong and reinforced. This oversized backpack measures 40cm by 60cm by 30cm. Durable backpack straps can be stored, and the body of the bag extended from 60 to 80cm, as it converts to an over shoulder duffle bag. This bag offers verstaility and tons of room to store your training gear. Various sized compartments allow perfect storage of small and large items.