Dual-flute design provides greater speed and control. Optimized for cordless drills in high speed. Rapid strike tip creates fast, accurate starts and generate less heat. Optimized geometry with black oxide coating to cut faster. More holesper battery charge for greater user productivity. Laser engraved reference marks easily stop on any hole size. 3 flat secure grip shanks reduces bit slippage in the chuck. Set includes: (1) #1 step drill bit 1/8"-1/2" by 1/32", (1) #2 stepdrill bit 3/16"-1/2" by 1/16", (1) #4 step drill bit 3/16"-7/8" by 1/16" and convenient carrying case to carry bits.