What material is the 10 ft. 16 oz. Copper Roof-To-Wall Flashing?

The 10 ft. 16 oz. Copper Roof-To-Wall Flashing is copper coated steel.

The 10 ft. 16 oz. Copper Roof-To-Wall Flashing is copper coated steel, to give it the strength to be formed and used as a roofing trim.