This is the Robinson Racing Pro Black Aluminum 48 Pitch 26 Tooth Pinion Gear.
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. Recommended for onroad, but they can be run off road. A wide selection of tooth sizes is available (Sizes 12 through 36 Teeth). Tooth number stamped on each pinion. 1/8 inch bore. One 5-40 set screw included. 1/16 inch allen wrench (NOT INCLUDED) fits the 5/40 set screw.
