Vinyl or metal letters that go in the indentation on your rear bumper where it says Cobra or Mustang. Ive found them in several colors but not the black chrome. I did find them once on the net, but can't seem to find them again.
OHH, OK. Yes. I personally like all of the reflective colors. I have reflective black on mine. Looks cool at night. The original Boss stripes were all reflective back in the day. I see the black chrome ones all the time. I'll post a link shortly.