Press in studs. 3.15" ( 80mm ) total length excluding protruding head. Pressing surface (knurl) diameter is 14.07mm approx. Drill/ream your drum/hub then press in. The unthreaded lead at the end is approx 7mm long. Not the correct size to replace front bay window bus studs that are too short - the pressing surface on those is larger diameter. Not exact pic.