1. GFCI TEST BUTTON: This versatile tester checks UK sockets for proper wiring and trigger function for GFCI. It tests your protection system to ensure household electrical safety, better protecting you from the risk of electric shock. 2. Bright LED Display: Light patterns are clearly labeled on the back of the device. The green LED indicators shine brightly even in strong sunlight. The builtin light allows for easy use in the dark, enabling quick and clear readings. 3. Easy to Use: Features a large, easytoread error chart with 7 different patterns: correct, ground open, neutral open, live/neutral reverse, live/ground reverse, live open, and live/ground reverse with missing ground. Provides clear indications for quick understanding and use. 4. Wide Application: Complies with CE, FCC, and RoHS safety standards. A versatile measuring tool widely used in schools, laboratories, factories, and other settings, saving time in diagnosing socket issues.