29 PIECE SET. 1/16"1/2" IN 64TH INCH INCREMENTS.SURFACE TREATED,? HIGH SPEED STEEL, JOBBER LENGTH DRILL BITS.A DEPENDABLE GENERAL PURPOSE DRILL? BIT DESIGNED TO PERFORM IN A BROAD RANGE OF MATERIALS IN THE IRON AND STEEL FAMILIES. IDEAL FOR PRODUCTION, MAINTENENCE OR PORTABLE DRILLING JOBS.