A wide selection of tooth sizes are available. Tooth number stamped on each pinion. One 5-40 set screw included. The "Pro" Pinions are precision machined from 7075 grade aluminum and anodized with a super hard jet black finish that not just hardends the surface but also protects the gear from corrosion and increases the lubricity by reducing friction and adhesion between the pinion gear and spur gear.
Its a Generation 3 Bearing which does not let water through the seal. Does not rust much. I still have the original one and spins freely without binding.