Electrical Socket Tester: Advanced socket tester to quickly detect whether the socket wire connection is correct or not. You can test the protection system to ensure the electrical safety of the house. Perfect to protect your safety from electric shock hazard.Bright LED Display: Light patterns are well labeled on the back of the device. Red LED indicators can be clearly illuminated even in direct sunlight. The tester has a built-in light so it can also be used in the dark, allowing you to read it quickly.DRC Function: This electrical tester tests RCD devices by simulating the condition of earth not connected, which works on the RCD sockets and confirms the operation of the earth protection device not connected. It tests standard sockets that are wired in parallel to RCD sockets. Be sure to use this function on normal outlets. It may cause the house wiring to trip.Portable design: compact size, light weight and convenient to use. With voltage backlit LCD display for voltage testing.7 LED Light Patterns: With 7 easy-to-read indicators to show outlet status, easy to judge: OK, Open Ground, Open Neutral, Reverse Live/Neutral, Reverse Live/Ground, Live Open and Reverse Neutral Live.