Customs Fog light covers?

I have a 46 pontiac with original fog lights. One of the bulbs had this cap on it and one didn't obviously for dimming. I would kind of like to find a match anyone have one or ever seen one?

 

it should be a 6 volt..mostly used in headlights before sealed beams

 

It is off a 6 volt bulb. Replaced with 12v bombs same size and style Sino have the bulbs I need just need the caps.

 

Those caps reflected the beam back to the reflector, softening the glare. Usually lost the first time a bulb gets replaced.

 

Try Dennis Kirk , Antique Harley Parts . I ran into this some years back . 6 volt bulb , wanted 12 volt bulb same strange style bulb . Dennis Kirk fixed me up fat , still running it today