Socket Tester can help you check house wiring and connection polarity of socket, it can also use to test leakage tripping. It is a profeional socket tester which rapidly detect whether the socket's wire connection is correct or not. WithD/GFCI test function, it is more practical and safe. Features: PORTABLE ELECTRIC SOCKET TESTER - Advanced socket tester for rapidly detecting whether the socket's wire connection is correct or not. Compact size, light weight and convenient to use. With voltage backlight LCD display for testing voltage. PLUG & PLAY - Designed withD/GFCI Test on, One Click to know the working state of the leakage protector. Perfect for protect your security against the risk of electric shock. BRIGHT LED DISPLAY - Light patterns are well labeled on the back of the device itself.