What is this for??

[oldtexasdog]

I just replaced my driver side headlight and noticed on the back (other side also) it has a second bulb plug marked 12V?? It has no bulb or wires going to it (Halogen lights) but it looks like it would illuminate the shark slits on the side of the light? 2008 Mustang GT
Thanks

 

[Rick Simons]

Photo?

 

[oldtexasdog]

I found out. It’s for adjusting the headlight.
Thanks