Product DescriptionMade from durable high carbon steel, this set will remove siezed up, rounded off screws. All screw extractors have a 1/4" shank which is suitable for drill use, they have a unique reverse spiral flute for maximum gripping power. Sizes - 3/16", 1/4", 8MM(5/16"), 3/8", 10MM, 11MM(7/16") & 1/2".Questions And Answers