Matl steel chrome-nickel molybdenum per aisi 4340 or e4340; phosphate coat per tt-c-490 finish; 4.000 in. Flanged diameter w/four 0.406 in. Diameter holes equally spaced on a 3.250 in. Diameter bolt circle; 0.625 in.-18 unf-3a thd end; 0.7495 in. Minor stem dia; 1.249 in. Major stem dia; 4.000 in. O/a lg