MX5 NC, All RX7's & RX8 take 20 of these and ordering one of these kits includes 20 spline nuts and one tool.
MX5 NA& NB, also MX5 ND take 16 of these and ordering one of these kits includes 16 spline nuts and one tool.
Available in Chrome or Black finish these are the patented design McGard Spline Drive nuts. Non-hex wheel nut which is both a light weight nut with more gripping surface area than the stock lug (to prevent loosening up under load), and a wheel lock.
If you look really close at the picture above you can actually see the two piece nature of this lug by looking into the lug at the bottom of the picture.
The part that touches the wheel (the "seat") stops turning and a bearing between that little ring and the rest of the lug allows the outer part of the lug to keep turning. What this means for you is that the lugs are not grinding against the surface of your nice new wheels and these lugs go on much smoother than any other lug nut choice.