Aluminum casting; anodized finish; formed in a 90 degrees arc; 19.500 in. Lg outside arc; 1.330 in. O/a thk; 4.500 in. O/a w; two rows of rectangular holes around top part of arc 0.625 in. By 0.375 in. Through thk of item; top row has 32 holes; bottom row has 28 holes