There is a part number...
I have got about 3 sets of these now... lost the air dam and damaged the radiator support last year, knocked the new air dam lose and had to replace the plastic push rivots about 2 months ago, and installed the new air dam from Mike in AZ and it was easier to just cut the old ones off the old air dam. There is a part number for the push rivots but they are too big in diameter... finally had the parts guy go to the body shop and got 5 rivots that fid, and they charged me $1 for all 5. If you get them in the auto store, you get ones that will fit, but have a very large head, and they are about $1 each. I'll have to post the dimensions when I get home... I have an extra one so that the next time I need one, I'll have one for the parts guy to use as a sample.