Aluminum alloy; per specification mil-w-45205; 23.250 in. O/a lg; 1.680 in. W; 0.190 in. Thk; item is welded to a rectanular steel shaped item that measures 5.380 in.O/a lg; 3.800 in. Wide on one end; 3.060 in. W on the other end; w/various size holes