Reverse thread design with dual tips quickly remove stripped or broken screws and broken off bolts without damaging surrounding area Upgraded quality M2 6542 tungsten alloy is harder than most extractors, allowing removal of far more fasteners including stainless, hardened steel and brass up to 12.9 tensile strength 1/4 in. and 5/16 in. hex shank screw extractors work with any adjustable chuck drill Designed to drill out and remove even the most stubborn stripped, damaged, embedded, rusted or painted-over screws and bolts Quick and easy operation: determine the proper size bit to use, and drill a hole with the fluted cutting end. Flip the bit to the tapered threaded end, and slowly reverse the damaged fastener out Sizes included work with the following size damaged fasteners: #1 (#4-7 screws; #10/5mm bolts), #2 (#8-10 screws; 1/4 in./6mm bolts), #3 (#11-14 screws; 5/16 in./8mm bolts), #4 (16-24 screws; 3/8 in./10/ bolts)