300M /Middle Stop Light on trunk

Some LV architectural lighting does indeed use 12v bulbs of the same form factor as some automotive lights. But the wattage must be correct, so check it carefully to make sure it matches, because there are about eight differently-rated bulbs in that exact form factor. They'll all fit and light up, but if you install one of too low a wattage, your centre brake light won't be bright enough. If you install one of too high a wattage, the centre brake light will be too bright until it melts.