This is a data storage unit for the Dreamcast. It hasn't been used in a long time, and I don't know if it still works. The battery was removed for storage. --- The following is product information generated automatically --- - Model: Dreamcast VMU (Visual Memory Unit) - Function: Game data storage, mini-game function - Ports: 2 connection ports - Battery type: Uses CR2032 battery - Buttons: A, B buttons, Mode, Sleep button Thank you for viewing.