What is this called?

[gafftapegreenia]

Maybe someone on here knowns. Been dealing with a lot of lighting fixtures that use this mounting system. It would be awesome if I knew what this system was called so I could order parts and find out what other variations exist. They seem to exist on everything from old green porcelain pendant shades to modern gooseneck commercial products.

 

[JonCarter]

The "ball" looks like part of the swivel mount often used on pendant light fixtures to allow them to hang vertically when mounted on sloped ceilings. It would seat into the mating speherical surface of an outlet box cover. The item on the right looks like fixture mounting hardware; probably has 1/8" pipe thread. Smoot-Holman was a manufacturer fixtures and accessories like this stuff, possibly out of business now. Take 'em to your local Graybar Electric and talk to a counter man w/gray hair; he should know.

 

[JonCarter]

From an old catalog.