6V light bulb not included.

The part that goes into the handlebar end is too thick and therefore does not fit in a standard handlebar.

I have tried to turn/grind that part, but because this part is not centric, a layer of chrome and/or copper remains here and there.

If you remove the entire chrome and copper layer, the diameter becomes too small.

One way to overcome this, is to use an adjustable reamer and ream the inside of the handlebar.

Unfortunately the original HELLA blinkers are not available anymore.....