These new diffuser fins conform to the underside of the stock oem diffuser. They add that special racy look while helping straighten airfoil on the back. The are made out of our 3/4" proprietary TM base material. They come in pairs, unfinished solid pieces, predrilled with installation holes. can be prepped and painted locally or left as is. Super easy to mount from behind diffuser, no need to remove any oem part , hardware included, FREE Shipping in USA