This piloted counter bore is ideal to countersink the head of the #RIVET-5 in wood, bone, or similar materials. It is NOT intended for use with metal! The 5/16" diameter has a #21 (.159" diameter) pilot. Use a #21 drill bit and pre-drill each rivet location, then follow up with this tool to piloted counter bore for the rivet head. Wear safety glasses during any drilling operation.
