HPI Racing Pinion Gear 20 Tooth (0.6M) E10 88020HPI's 0. 6M pinion gears are a perfect fit on the E10 making gear ratio adjustments quick and easy. Each pinion is precision machined to the exact factory tolerances for a smooth gear mesh. A wide range of gears is needed for the various stock and modified motor racing classes so most racers will carry several different pinion sizes in their pit boxes. Each gear is stamped with the number of teeth for easy identification.