The Tamiya 72008 4-Speed Worm Gearbox kit includes one brushed DC motor and all the gears and parts to build any of the four possible gear ratio configurations: 84:1, 216:1, 555.4:1, 1428.2:1 . The four gear ratio options give you the flexibility to choose the best speed and torque for your project.

The kit includes step-by-step illustrated instructions in both Japanese and English. The kit can be built with just a screwdriver, but the instructions recommend having side cutters, pliers, and a modeling knife on hand.