Direct replacement for NA, NB, NC and ND. This 1.3 bar (18.8psi) version is higher pressure than the factory Mazda 1.1 bar (16 psi) cap.

Fits 1990-2005 NA & NB factory radiators
Fits 1990-2005 NA & NB Koyo radiators
Fits 2006-2015 NC factory plastic expansion tank
Fits 2006-2015 NC Moroso aluminum expansion tank
Fits 2016+ ND

Koyo designs its radiators to take all factory spec parts which means your factory cap will fit, and your factory plug will fit, and your factory fans will bolt right on.

But for those who want an upgraded new cap to go with their new Miata Koyo Radiator...or stock radiator...here you go.

Koyo Racing 1.3 Bar Hyper Red Radiator Cap raises the cooling system pressure to 1.3 bar to improve entire cooling system flow. The higher pressure cap reduces the chance of air from entering the system compared to the factory cap. It also improves the look of your engine bay.