I no longer have a need for this. My son used it for commuting on his motorcycle for a few months. This is the information from the website:
The KAPPA K26 cargo box has an internal capacity of 26 liters. Like the other KAPPA and GIVI cargo boxes in our collection they are built to last. Each Kappa K26 cargo box is lockable ensuring that the contents are kept dry and secure.
Removing the Kappa K26 is easy. Simply insert the key and push in the red button and the K26 can removed and carried around or swap out the K26 with any of the other GIVI and KAPPA cargo boxes or bags in our collection.
You can easily fit 1 full face helmet or other items inside the KAPPA K26 cargo box.
Specifications
Length: 30 cm
Width: 38 cm
Height: 38 cm
Capacity: 26 liters