Heat Treated High Carbon Steel Construction, Corrosion-Resistant Finish, Removes Broken Screws, Bolts, and Studs without Damaging Hole Threads. Contents include: 5-pc. Screw Extractors: 1/8 -1/4 , 1/4 -5/16 , 5/16 -7/16 , 7/16 -9/16 , 9/16 -3/4 ; Complete with Storage Case.