You're driving a Miata. There's an Expedition behind you. Make sure they know 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 1156 is the correct bulb for the third brake light on an NB Miata as well as thousands of other applications around the industry. At 310 lumens, it's brighter than stock and will give instant notification of your intent to stop! Red in color.
310 lumen: Diode Dynamics HP11
1156 cross reference: BA15S, 1141, 2396, 67, 87, 12088, 1156NA, 97NA, 1095, 93, 97A, 1295NA, 97, 3497, 1073, 1295, 1195, 1156A, 7506, 199, 631, 1156ST, 1073LL, 1156LL, 7506L, 3497LL, 7506ST, 1156ALL, 97LL, 7506LL, 93LL, 631LL, 1141LL, 5008, 5007, 1155, 89, 57X, 105, 1003, 98, 1003LL, 67LL, 89LL, 105LL, 5008LL, 5007LL, 1155LL, P21W