Here is a vintage headlamp light marked with the MILLER Diamond -- the bolt on the bottom is marked with MRW.

It is about 4" in diameter and 5" long -- including the mounting, it's about 5 1/4" high.

Condition is as pictured.  I don't have a way to test the bulb, but its filaments look intact to me.  The reflector surface is bubbled a bit in a spot close to the bottom

I am always happy to combine shipping.