Kahtec
http://www.kahtec.com/smart_stop.htm
I installed one of these on our BRZ and our Outback. On the Outback, the 3rd brake light blinks 5 times each time you apply the brakes. If you stay on the brake the light remains solid.
On the BRZ, the 3rd brake light blinks 5 times, remains solid, but will only blink again if 8 seconds elapse between brake application.
Because the BRZ is so low, I felt I needed something to alert distracted drivers. I also installed an Intec high mount 3rd brake light.
Kahtec offers several types of flashing modules. Installs in minutes and can easily be uninstalled.