mazda-parts.com or the dealer? The website seems pretty foolproof to ensure you are ordering the correct part -- click the picture to verify.
Same as NA or NB Miata, what is the problem?
Good luck with that. Went to the dealer after I Stripped one of mine and was with out a car for 3 days because they didn't have a part number for it here. They disassembled the hub and had to break the old lugs off before looking to see if they had a replacement. I was not amused.
The ARP part#s we use are
100-7720 ARP http://arp-bolts.com/kits/ARPkit-detail.php?RecordID=80 shows Mazda Miata rear '94-'05 Wheel Stud Kit
100-7719 ARP http://arp-bolts.com/kits/ARPkit-detail.php?RecordID=79 shows Mazda Miata front/rear '90-'93, front only '94-'05 Wheel Stud Kit
The listing shows the knurls
The ARP part#s we use are
100-7720 ARP http://arp-bolts.com/kits/ARPkit-detail.php?RecordID=80 shows Mazda Miata rear '94-'05 Wheel Stud Kit
100-7719 ARP http://arp-bolts.com/kits/ARPkit-detail.php?RecordID=79 shows Mazda Miata front/rear '90-'93, front only '94-'05 Wheel Stud Kit
The listing shows the knurls