This IRWIN HANSON 536/526 Series 6-Piece Straight-Flute Screw Extractor is designed for softer materials or thin-walled pieces, so much as pipes and fittings. The screw extractors can both left-handed and right-handed rib parts and are designed to ease extraction because they do not expand the material as it 's removed. The extractor and recommended drill bit size are etched on each IRWIN screw extractor.