It's a cap that seals the back of the head lights. I bought one assuming that they were the same from coupe to sedan but of course the coupe is different.

I may have to use duct tape lol
here is a pic of the wrong one

 

Check this link and it should be #9 and there is a different part for left & right https://discountinfinitiparts.com/pa...iagram=3846025 EDIT, guess that didn't help since it's N/A

 

I saw that but it doesn't seem as though they sell it separately