Those are called rivets which are extremely durable and strong when installed correctly using a rivet gun, however, standard stainless bolts and nuts sourced from a local hardware store will work just as well.
I've purchased quite a bit from Outmotoring, from hood scoops to GP diffusers and coilovers. They are quick to help with questions and the products are great for the money.
Aaron
Excellent fit. I bought the matte black to try and match the rest of the trim and it looks factory installed.
Removing the OE chrome grill "nuts" was a bit of a pain, so I elected to just snap the plastic threads off rather than attempt to remove them. I wouldn't plan on keeping the OE grill as the plastic threads and stamped nuts are practically destroyed no matter how gentle you are.
The upper grill snaps in and use the same fasteners as the OE. The new stamped nuts can be a bit annoying, just seat the nut on the ball of your thumb and turn. Once the nut cuts into the plastic use a nut-driver to snug up--don't over tighten.
The lower grill just snaps in. I cleaned and plasti coted the bumper black, as you can see the bumper color behind the new grill--my car is red so it really stood out.
This grill makes the car look so much better and more up to date. I really like it.
*plasti-cote is your new best friend*
John
These guys are the best. Their knowledge of these cars is over the top. You get so much more than parts here; you get knowledge and amazing customer support. I just won't deal with anyone else anymore, this place is that good. Than you Aaron and everyone for making a great place to keep all my MINI's going strong!