This is a Robinson Racing “Aluminum Pro” 64 Pitch 52 Tooth Pinion Gear. The “Pro” Pinions are precision machined from aircraft aluminum, lightened and then they’re coated twice with a super hard, black anodize. Recommended for onroad, but they can be run off road. 1/8 inch bore. One 5-40 set screw included.
Robinson Racing “Aluminum Pro” 64P Pinion Gear (52T)