16 gauge mild steel. Powder coated for indoor or outdoor use.

Item does not come with mounting hardware.

Product Dimensions (inch):

12 - 11.5" x 11.5"

15 - 14.5" x 14.5"

18 - 17.5" x 17.5"

24 - 23.5" x 23.5"

30 - 29.5" x 29.5"