This is a vintage Western Electric ROTL-System test set. This is model H-310-150. This is a large complex unit, very cool piece of Western Electric Rotary Phone History. This was powered from -48 VDC. This is in good condition, There is scratches on the outside case and some pencil marking on front panel. This is not tested, I do not have the external power supply for this unit. This unit is very rare and hard to find.