rotary run racing headlight question
 

I have a set of rotary run racing headlights housing but no actual lights. as they came on the car I recieved I have no instruction or anything. they are mounted already.
what kind of lights will fit?
is there a model of light that I can look up? like a number or style or diameter to search by?

I just hit search for this.,,BING brings up a couple links.