Aluminum alloy, qq-a-250/11, 6061-t4; chemical film finish mil-c-5541, class 1a, gold; 5.160 in. Lg, 2.660 in.W, 0.880 in. High, 0.063 in. Th; corners to be welded and ground smooth; 4 0.125 in. Diameter holes; 4 holes 100.0 degrees csk x 0.289 in. Dia