This is a adjustable power transformer.
Plugs into any home or workshop power outlet. With 120 volts AC input, it allows you to vary the voltage from about 79 volts to 155 volts AC. Allows you to compensate for over or under voltage.
Made by STANDARD ELECTRICAL PRODUCTS CO. of DAYTON OH.
5 AMP output.
9 inches tall x 7 inches wide x 5 inches deep.