The Martindale BZ101 Check Plug is a rapid-response socket tester that provides a wiring check of 230V 13A UK wall sockets as soon as it is plugged in. Fault presence or absence is indicated by both the audible buzzer and the triple LED display and the sequence of LEDs will indicate the nature of any fault other than earth-neutral reverse. It is also possible to use the check plug as a basic fuse finder which warns when a fuse is removed.