General description The Irwin HSS TCT Tip Drill Bit is designed for precision drilling in various hard materials, including hardened steel, cast iron, bronze alloys, and manganese alloyed steel. Featuring a Tungsten Carbide Tipped (TCT) design, this drill bit ensures efficient performance and durability. Technical specifications Diameter: 7.0mm Total length: 109mm Working length: 69mm Material: Chrome Vanadium Steel, hardened to 56 Rockwell C Carbide tip hardness: Up to 50 Rockwell C Usage For optimal performance, it is recommended to use a coolant while drilling with TCT twist drill bits. Irwin suggests a coolant emulsion of 3-6%, which helps to extend the lifetime of the drill bit. Other information