Assembly required.
Tamiya’s twin-motor gearbox consists of two independent brushed DC motors and gearboxes in one compact housing, making it perfect for small robots. You can assemble the gearboxes to have a 58:1 or a 204:1 gear ratio.
The Tamiya twin-motor gearbox is a small (3-inch long) plastic gearbox. It contains two small brushed DC motors that drive separate 3mm hexagonal output shafts. There are two ways to put the kit together: with a high-speed 58:1 gear ratio or with a slower 203:1 gear ratio. Either way, the motors provide plenty of power to drive any small robot.