High-strength split one-piece machined 2-gear 13/17T pinion gear module from tough 7075 T6 aluminum and particularly hard coated for superior energy, light-weight, and high durability. Developed on a special gear unit, all pinions feature ultra-precise enamel shaping and ultra-true operating for vibration-free operation. Fine inside threading permits simple installation. Each pinion is fine etched because of the tooth quantity for fast & effortless identification.