The Talking Machine Forum — For All Antique Phonographs & Recordings

Am I correct: is this some sort of volume adjuster for ear tubes? Anyone know with which machine(s) it goes? (It's too small to fit an Edison O reproducer, for instance.)
Any value?

Thanks! -Michael

I believe I've seen those on Dictaphones.

The little gizmo is the volume control. Weren't these also used with ICS Language courses, and the Language-phones?
Harvey Kravitz