This is a CRT TV Picture Tube Tester and Rejuvenator. They were extensively used in the day of Colour TV Picture Tubes and their service. I really have no idea what this is worth now. I am a qualified Television Technician and used to own my own business and this was a great piece of kit to own in the day and expensive. I have added photos which show a variety of sockets which fit almost every brand of TV and wiring configuration.