The BMW R12 was produced with 3 headlights total during its production run. Each headlight was used with the respective generator or magneto. The first lights used were the EAS 170 with the small waltzentacho. Each light is very similar to one another but one light has a charge light and one without. The BOSCH 245RS108 generator was used with the headlight which had a small charge light on the left and a fuse on the right with the key in the middle. If your motorcycle was equipped with a battery ignition it had this type of light.
If your motorcycle had a BOSCH D2B magneto than you should only have a key with no charge light since its a magneto and there is no need for a charge light. This headlight is the most common one that left the factory during its production run. It is also the most biggest mistake on all BMW R12 restorations.
Here is an original EAS 170 light for the BMW R12 to be used with a D2B magneto from BOSCH. Also to note is the original Veigel speedo.