5pc Rounded Bolt Screw Remover 1/4" Hex Shank Fits SAE & Metric Cr-Mo Steel What the pros use on stubborn rounded bolts. Manufacturer's lifetime guarantee Unique spiral-cut teeth bite into head and provide excellent grip so you can turn out bolt Hardened and tempered Chrome-Moly steel alloy for superior strength and durability. 1/4" hex quick-change shank fits power drills and impact drivers One set fits SAE and metric size bolts from 1/4" (6mm) to 1/2" (12mm). Also great on screw heads and studs Includes nylon canvas pouch to keep all pieces organized and easy to find