Hanson Straight Flute Screw Extractor, for removing broken screws, studs and bolts in soft materials, or thin-walled pieces such as pipe and fittings. The straight tapered flute will not expand the piece being removed, the broken piece is removed without damage to threads. The correct drill size is stamped on each screw extractor. Use drill size 15/64. Irwin tools are made of only the finest materials, manufactured to exacting tolerances.