Advance with gear box to change gear ratio for manipulation of torque without servo motor batteries or receiver. You may also use this kit with the wired KELVIN® SUMO® Car Wrestlers. Includes  gear boxes with adjustable gear ratios,  1.5–4.5 VDC motors, wood base and  wheels. Does not include electronic materials.
NOTE: Does not include servos, receiver or batteries – use those supplied with the SUMO Wrestler® W2™, #842077, or the SUMO Wrestler® W4™, #842078. Servos are also sold separately.