Hi, I ordered a set of these caps. I have Keystones on my '79 Ranchero Gt. I actually used the caps on an 2004 Mustang, with Cobra wheels. This is the perfect fix when your chrome is pitted around the center wheel opening. The Cragar cap fits right over the opening. The backing plate is screwed on from the inside of the wheel. It looks great on the wheel, and makes them different. I get many compliments. Gary in Va.