Screw-Extractor-Set-6-Piece-Blue Spot-Tools-22304-p-The-Blue Spot-Screw-Extraction-Bits-are-manufactured-from-carbon-steel-&-feature-a-reverse-thread-They-are-used-to-remove-broken-damaged-screws-&-bolts-Simply-insert-into-pre-drilled-hole-within-screw-&-operate-drill-in-reverse-to-remove-screw-without-damage-to-hole-The-square-end-also-allows-use-with-a-tap-wrench-Suitable-for-screws-3-25mm-diameter-p-Blue Spot-Tools-22304-Screw-Extractor-Set-6-Piece