King Crown Gears feature light weight, less friction and great gear mesh for inline chassis (Womp-Womp, EDGE and HoleShot Drag Cars, Etc.) They are precision molded from virgin nylon with an integrated aluminum hub. Each gear has two predrilled and tapped holes - one on each side of the hub and one 4/40 allen head set screw is included. Photo shown is generic for identification purposes, this part number is for the specific gear (axle size/pitch/tooth count) described in heading. We also have a 3/32" axle sleeve so these gears can be fitted to a 3/32" axle.