Aluminum alloy, qq-a-250/7, alloy 6061-t651; anodized, mil-c-8625, type 3, class 2, color black; 2.260 in. Lg; 1.750 in. Wd; 0.440 in. Thk; 1 center hole 0.8745 in. Min and 0.8755 in. Max dia; 4 holes 0.136 in. Dia; center area recessed to 0.180 in. Deep by1.600 in. Lg by 1.500 in. Wd