Irwin 11135ZR Screw Extractor and Drill Bit Set, 35-Piece; These drill bits are designed to remove broken studs, bolts, socket screws and fittings; This drill bit set features an aggressive left-hand spiral design for extra gripping power; Each drill bit has a spiral flute for higher grip when resistance increases; Drill bit size and recommended drill bit size are etched on each tool for easy identification; Spiral screw extractors: EX-1, EX-2, EX-3, EX-4, EX-5 and EX-6