Aluminum alloy, qq-a-225/8, alloy 6061, t6, anodize, mil-a-8625, type 2, cl 1; 3.250 in. Lg; 2.760 in. W; 0.750 in. H; 0.572 in. Center hole dia; 0.280 in. Min and 0.287 in. Max mtg hole diameter four places; 0.138-32 unc 2b and 0.280 in. Min deep threaded holes two places