This sale is for a new old stock Lorain model M-7.5 Sub-Cycle static frequency converter.    These were made for Bell System, Western Electric to convert the 120 volt, 60 cycle line voltage to 90 volts, 20 cycle ringing voltage to power telephone ringers.   This is one that was never put into service, but has been in storage easily over fifty years.   One area on the base of this item is missing  some paint, a consequence of the long storage. (See photos.)