304 Stainless Steel, precision cut using a water jet, Polished to a bright finish.

Easy to install: remove existing 5 screws and nuts, align center hole and re-install screw and nut (do not tighten), insert left screw and nut, then right screw and nut, then 2 inside screws and nuts. Tighten (CAUTION: DO NOT over tighten) starting from the center outward.