This is a replacement package of four steel wheel adapter shafts for the Lightning Series, as well as the D8 and D8T 1/8 scale vehicles. Length 11/16" (17 mm); Diameter: 1/8" (3 mm). These are the small pins that pass through the wheel adapter and the axle. They keep the wheel hex in place, and are held down by the set screw that threads in through the end of the axle.