huge heavy round milk glass plateau, vitrolite tray for dental/medical instruments

Huge heavy vitrolite white glass tray, a mid-century vintage dental, medical or lab work surface. This doesn't look as though it's had much if any use! An interesting old piece with a vintage industrial style.

It's about 14 1/2" in diameter overall, marked on the back with a makers mark we've not been able to decipher. It's nice and clean, without chips, roughness or scratching.