Mystery object

Although not used recently, this object used to perform a very specific, useful function, and may do so again. Answer tomorrow. Thanks to jensphotos for hosting Tiny Tuesday on the theme of Mystery Object.
Added on Wednesday:
This mystery object is a brush to clean a pick-up stylus for playing vinyl records. The round metallic part is a mirror to make it easier to find the stylus. After 50 years or so, the mirror is now tarnished and not very good. Thanks for trying to identify it.