The Sandoseru is a luggage compartment that attaches to a school backpack (randoseru). It's easy to attach with snap buttons and fits backpacks up to 35cm in height. I purchased it, but it has been stored at home without being used. The outer packaging has been opened. Please consider purchasing if you understand that this is a used item. No returns. - Color: Black - Compatible backpack size: Height 32cm-35cm, Width 24.5cm-27.5cm, Depth 19cm-22cm - Features: Easy attachment with snap buttons