Originally Posted by silverbear
I'd use LED lights in there. There are Cree bulbs you can get for not too much. Where did the light come from? I'm guessing it is old and from a boat. Brass is mighty fine, too. Whatever it is, it will look really good on your bike. Nice find!
It's a side light from a Cadillac, I believe from around 1915 or so. They were actually made in left and right versions because there is a side lens to warn side street traffic. Being a side light it is smaller in scale than a headlight which is HUGE.