It might be made from brass or bronze. It has a more bronze looking coloring to it, but it might just be tinted brass. Overall dimensions: 13 3/8" wide x 4" tall.
Opening dimensions: 11 1/2" wide x 2.25" tall. Mounts with fourscrews (not included). Overall dimensions: 12 1/2 wide x 3 1/2 tall. It stands out about 2 1/2.