GIR BIRU SET TAMIYA ORIGINAL PRO TAMIYA PRO HIGH SPEED GEAR SET - MS CHASSIS/GEAR RATIO 4:1 Offering the high speed gear included with Mini 4WD PRO Nitro Thunder and Nitro Force as a separate grade up part to widen setting choices. Mini 4WD PRO racers equipped with small wheels and super speed 3.5:1 gear may experience dulling of acceleration on courses with high number of curves, as the motor becomes stressed when frequent deceleration is required. In order to improve acceleration in such cases, utilize this 4:1 High Speed Gear in conjunction with the REV-Tuned or other high revolution motor. Also useful as spare part to replace old or worn out gears.