Made of aluminum that is lighter than iron; Laser-cut aluminum boards to a thickness of 0.08 inch (2 mm) to ensure strength. The surface is coated with a black semi-gloss coating, and it blends into the car body and is resistant to rust. The in-car device is designed specifically for the Mitsuvasan Kowa (See compatible models), and the case size is extremely compact, and it will fit almost perfectly in the case. A cushion spacer is also attached to prevent rattling. Keys are made by Tochigiya which supplies parts for Eigis ships, jets, and bullet trains. In order to make the ETC case as small as possible. Comes with rubber grommets to protect the wiring. Depending on the mounting position, the car unit may rattle inside the ETC case. Comes with 2 cushion spacers, so you can adjust the cushion spacer in the event of a rattle.