Lead screw pulls bit into work eliminating extra pressure and strain * Specially heat-treated alloy steel resists damage from nails * 7-1/2" length * 3/8" hex shanks, 1/4" bit has 1/4" hex shank * Includes bit sizes 1/4", 3/8", 1/2", 5/8", 3/4", 7/8" and 1";