Obsolete term for compartmentalized striplights or borderlights, such as the R40 Strip. Used circular glass color media called rondels, or roundels.
The term is still used in the rental industry, especially to refer to multi-cable break-outs built for strips (usually tails 1,2,3 are 3'-0", while tails 4,5,6 are 13'-0", etc).
Photo by Skip Murray.
According to McCandless' A Method of Lighting the Stage:
The company was the National X-Ray Reflector Company, publisher of the book Lighting From Concealed Sources, 1919.