Well in the case of front and back LEDs it gets wired in with them but in this case it gets wired in instead of the rears. If you read my first post I said they sell them at custom HD shops to replace the regular bulbs with LEDs. V Twin , Drag Specialties , or Custom Chrome sells them not sure what one or maybe all 3 do. I imagine HD dealers have them and wouldn't be suprised if other bike shops sell them too.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!