Email PrintMaterial : C1018 or Equivalent Heat Treat : Carburized, Hardened and Ground Finish : Black OxideThese are plain keys designed for fixtures to fit one specific machine table. These keys are hardened & precision ground all over Inch Part No.ABCDTSlot SizeScrew Size S 01-01-0023/41/21/21/49/321/21/4-20 01-01-0053/41/25/85/163/85/85/16-18 01-01-0111¼1/23/43/83/83/45/16-18