Router bits are listed as 1/4", 3/8", 1/2" and 5/8" which is exactly what I needed. Got cutters 6mm 10mm 13mm and 16mm, useless to me. Cut out a plug with a 1/4" cutter (?) and try to plug the 1/4" hole, the plug fell out, too small! take it off before I even had a chance to try it. Waste of time and money, will come back for a refund.