The ST120+ Socket Tester with a GFCI test button and beeper from Fluke is the perfect tester for electricians and electrical inspectors, home inspectors and technicians who need to verify the correct wiring of outlets. The bright, easy to see LEDs let you know if an outlet is miswired and the integrated GFCI test button gives you peace of mind by allowing you to verify the proper operation of GFCI equipped outlets.The addition of a switchable beeper makes the ST120+ even more capable. In addition to providing an additional level of safety by beeping whenever voltage is present even with a miswired outlet the beeper also helps you save time identifying circuit breakers.Just plug in the tester into an outlet and make sure the beeper is switched on. Then, when you flip the corresponding circuit breaker for that outlet, the beeper will turn on or off, letting you know that you found the right breaker.These features packed into the compact yet rugged design of the ST120+ make this the perfect tester to take to every job.