I have the (fat) head light with a pair of tail lights. I did a short ride this evening with the lights - first time in a long time, as the days are getting shorter. Everything worked well enough, but when I got home and into the garage, I pressed the "turn signal" button for a right turn, and saw that I had mis-mounted the tail lights so that I was actually signaling for a left turn. I've tried to keep the two tail lights so that the left light is always on the left of the headlight and the right is on the right, but I messed up.
I guess next ride, I'll test the turn signals before I start and make sure I haven't crossed my hands again.
It seems clear that I should mark the lights as L and R. Does anyone have a suggestion as to how I can do this? Maybe I should use a sticker? Or could I use a marker - white or yellow on the black case?