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 been ordering parts from Outmotoring's site for a few years now after having some bad experiences from other Mini part sites. Although I have only had a few order errors, Outmotoring has corrected it quickly both times. If 'to err is human' than Outmotoring is 'more human than human'. Keep up the good work guys and I'll keep buying from you!
Rick Dallimier
Actually spoke to an extremely professional, but moreover knowledgeable young man about my issue....fast,easy, and good....usually you can only pick two of those, all three is rare commodity these days. Well done!
Lt. Col. S.C. Gardner
(Oak Hill Farm)
Excellent experience! We needed an exhaust manifold in a hurry for a customer's MINI. Out Motoring answered our questions and got one shipped out very quickly. Five stars for sure.