Martindale BZ101 Check Plug with Sounder.
The Buzz-it is a fast and easy way to ensure 13A sockets are wired correctly in the same way as the Check Plug above.
The Buzz-it gives an audible signal in addition to the three neons lighting when the wiring is correct. This allows for awkwardly placed, or not easily visible, sockets to be checked.
The Buzz-it can also be used as a basic fuse finder - when the correct fuse is pulled the buzzer stops ! For a more sophisticated fuse finder, with no hearing distance limits and no risk of pulling the wrong fuse.