Miatas that see track use can be pretty hard on their front hubs. It`s a good idea to inspect them regularly, and replace them before they go bad. Hub failure can mean a runaway wheel - nobody likes that.
For the NC, we have a bolt-in upgrade that will install much larger and stronger bearings. Highly recommended for any NC that sees track use, especially considering the amount of rubber these cars can carry.
Price is for one hub/bearing, two are needed per car.