High-strength separate one-piece machined 2-gear 13/17T pinion gear module from tough 7075 T6 aluminum and specially hard coated for superior strength, light weight, and high durability. Created on a special gear machine, all pinions feature ultra-precise tooth shaping and ultra-true running for vibration-free operation. Fine internal threading allows easy installation. Each pinion is fine etched with the tooth number for quick & easy identification.