Starting in 2018 Mazda changed the MX-5's tire pressure monitoring back to a traditional system using sensors inside the wheels. When ordering new wheels for your 2018+ MX-5 you'll either need to swap the sensors from the factory wheels or purchase a new set.
These are not necessary if you have a 2016-2017 MX-5.
We get these directly from Mazda, please allow a few extra days for these to arrive in to us.