Up to 3 to 4 times stronger than the typical single purpose bit. Cuts through hardened steel, ceramic tile, marble, plastic, cast-iron, concrete, glass, and woods. Negative back grinding enables tip to bore through materials with a filling action. Designed for rotary or percussion drilling. Cobalt and tungsten carbide drill bit tip designed for maximum hardness, resistance to heat up to 2000 F (degree Fahrenheit), and wear. Chrome vanadium steel shank. Set includes 1 each: 1/8", 3/16", 1/4", 5/16", 3/8".