2chromium steel sae 52100 per mil--s-7420, chrome plate type ii class 2, per qq-c-320; 1.000 in. Dia, 0.450 in. Thick; one hole 0.078 diameter before csk, csk 82 by 0.120 in.Dia; in center 0.219 diameter counterbore 0.312 in. Diameter by 0.009 in. Deep, 0.099 dia