Steel alloy, mil-s-13326, plate form, class 90 to 100, condition a/a, 3/4 in. Thk material, 6-1/2 in. W by 8 in. Lg base w/four 11/16 in. Diameter mtg holes spaced 4-1/2 in. C to c on w and 6 in. C to c on lg, 4-13/16 in. H tongue w/attachment hole 1-9/16 in. Dia