GE "VR" series acorn fixture in Fullerton, CA

There are dozens of these in this neighborhood in Fullerton, CA. Similar to a gumball, but with more of a "low bay" design, with a deep reflector and shallow drop lens. They are on series circuits, originally incandescent, now HPS with plug in series ballasts. They can be changed back to an incandescent simply by unplugging the ballast and plugging in a plain mogul socket designed for series circuits. I know of a few remaining as incandescent in Pasadena, CA in the same area with the radial waves. Also, in the suburbs of Detroit, DTE Energy still has some of these scattered here and there on residential streets, converted to mercury vapor.