It is drilled to use a .750" crank bolt and has the standard six 3/8" bolts on a 2.782" bolt circle that the dampner has, as well as six 5/16"-18 drilled and tapped holes so the racer can bolt the dampner shell to the spacer. Spacer is 1.100" thick with a .500" step to register the dampner shell to the spacer. Overall thickness is 1.600".
This spacer is also great for splined crank hubs that protrude thru the front of the spacer, racer can slide the spacer over the crank hub and then torque the crank bolt to the hub.