High-strength split one-piece machined 2-gear 13/17T pinion gear module from tough 7075 T6 aluminum and particularly difficult coated for superior power, light-weight, and high durability. Developed on a unique gear product, all pinions function ultra-precise enamel shaping and ultra-true running for vibration-free operation. Fine inside threading allows simple installation. Each pinion is okay etched because of the enamel amount for quick & effortless recognition.