its the plastic interior that rides under the wing...there are two types.......the ones that everyone is telling me about our what is the lower third brake light ....(the plastic piece under the wing that the third brake light is mount there.) then you have the uber rare top hatch mounted third brake light model 162's.......there piece under the wing has NO cut out for the third brake light cuz there is no need so it covers the whole underside of the wing without leaving paint showing. i realize its pretty hard to describe....ill take a pic of the underside of my hatch and ill point to where there should be plastic but theres not. i know confusing.