This is a Serpent Spiral 10T Pinion Gear. The 10T pinion and 43T ring gear (SER600696 - not included) have a slight spiral cut. Precision machined from top quality steel and hardened, these gears run super true and smoother than the straight cut gears. These are included as standard equipment on the Cobra E-truggy and are an excellent upgrade for the Cobra Nitro Truggy.