Aluminum alloy, welded construction, consist of top angle bracket 3/16 in. Thk by 1-14 in. W by 10 in. Lg w/four 11/32 in. Diameter mtg holes, support angle 3/16 in. Thk by 1 in. And 1-1/2 in. W by 20.1/8 in. Lg w three 3/8 in. Diameter mtg hole at upper and one 13/32 in. Diameter at bottom location