These pieces fit around the driver and passenger side rear side marker lights of your 2010-current Mustang (fits V6, GT, and GT 500 models) that are on the  sides of the rear bumper cover.  You get both sides.  These pieces are laser-cut from 18ga mirror stainless steel with a low-profile for a sleek but noticeable appearance.  They will never rust, peel, or oxidize. These pieces adhere with pre-applied 3M double-sided tape; just clean the area, peel the liner and stick it into place.

Additional photos are shown in the additional pictures below the main picture above.