You're driving a small car. Let everyone know when you're stopping.
We use LEDs from Diode Dynamics because they're the best ones we've found. They're made in the US to high standards, not just the minimum price. They've got constant-current circuitry to protect the bulbs from transients and offer a three year warranty.
The 7440/7443 is the correct bulb for the brake and tail lights on an NB or NC Miata - as well as thousands of other applications around the industry. The 280 lumen option is a good replacement for stock. The 310 lumen option is the HEY YOU IN THE SUV PAY ATTENTION option. They are red in color.
280 lumen: Diode Dynamics HP48
310 lumen: Diode Dynamics HP11
Note for other applications: This is a 7443 bulb, which has both a high and low power filament. If used in a 7440 single filament socket, it will only illuminate the high power filament.
For NAs and NBs only (not NCs), if you have cruise control and you replace all of your brake lights (not tail lights), you'll need to add a resistor to keep the cruise control functioning. If you leave a single incandescent bulb, the cruise control will continue to function with no issues.
7440 cross reference: 7441, 992, 7440, 7440ST, 7440AL, 7440LL, 7440A
7443 cross reference: 7444NA, 7443, 7443ST, 7443LL