9aluminum alloy qq-a-250/11, 6061-t6; anodic coating per mil-a-8625, class 2, type 2, black; 1.505 in. Lg; 1.25 in. W; 0.38 in. H; circular shape w/two flat edges and a gap; one 0.146 to 0.152 in. Diameter mtg hole w/0.276 to 0.291 in. Diameter 100 degrees countersink