I've had this for a while but I can't seem to figure out what it is supposed to test. It has a male household plug and outlets/bulb sockets wired into it. Also some female receptacles and an automotive bulb socket. It has a cradle with two connectable leads for whatever is being tested. It utilizes a Model T style coil as can be seen and appears very "factory" built. Can anyone provide any insight?? Thanks in advance.