Hello Else, Check out Paul Goffs page NORBSA. He sells indicators in 6V or 12V with LEDs, with flasher units, and either -ve or +ve earth. I like these and have fitted them to my bike (nacelle). The lens protrudes slightly at front, so they can be seen from the side much better. They are about 45mm OD from memory, but I wanted to be seen as opposed to looking too original.
Col