We supply our taps in Carbon steel whenever possible. If one should break off in a hole, the remains can be "shattered" with a punch for easy removal. All numbers in chart are shown as Nominal Size, Tap Drill Size, Clearance Drill Size. Mfg: Irwin Industrial Tool Co. SPECS: Those taps marked with * are Japanese-made, carbon steel. These taps marked ** are high-speed steel. Others are U.S. made.