Penn Engineering# KFE-3.6-11ET. Carbon steel non-threaded standoff. 11mm long. 3.6mm I.D. Designed for unplated through-hole applications. A broaching fastener is a knurled-shank fastening device that can be pressed into a hole to provide a strong threaded attachment point in non-metal materials. Specially formed axial grooves around the shank of the fastener "broach" or cut into the material, creating a firm, interference-type fit resistant to rotation.