Master Mechanic, 23/64" x 4-7/8", high speed steel with cobalt drill bit, 135 split point, jobber length, straight shank, 135 split point design with 4 cutting edges allows quick penetration & eliminates walking, 8 percent cobalt content provides heat resistance & delivers maximum cutting efficiency at temperatures in excess of 1000 degree Fahrenheit, recommended for drilling in hard metals such as heat treated steel, stainless steel, chrome, manganese steel Plus titanium & Armor plate, Carded.