Voltage and frequency range: ST05D:220-250V,50-60Hz(EU PLUG) ST05B:110-125V,50-60Hz(US PLUG) ST05E:220-250V,50-60Hz(UK PLUG) Advanced outlet testers can help you check house wiring and outlet connection polarity, and can also be used to test for earth leakage trips. It is a profeional socket tester that can quickly detect whether the wiring of the socket is correct. With RCD test function, it is more practical and safer. Selling points: 1.Three kinds of plug for your choice:ST05D(EU),ST05B(US),ST05E(UK). 2. Portable Socket Tester --- Advanced socket tester, used to quickly detect whether the wiring of the socket is correct. Small size, light weight, easy to use. Backlit LCD display with voltage for testing voltage. 3. RCD function --- Designed with RCD button, one key to know the working status of the leakage protector. Great for keeping you safe from the risk of electric shock. 4. Bright LED Display---Clear and high-brightne screen display, can light up clearly even in strong sunlight, the product can also be used in the dark, allowing you to read quickly. 5. ST05 socket tester has 6 circuit status display modes---helping you to judge the wiring status simply and quickly. The 6 statuses include: correct wire, miing zero wire, fire zero reverse, miing ground wire, fire ground reverse, mismatch and lack of land. 6.Wide range of applications - Widely used for electrical maintenance testing, office socket testing, power strip testing and wall socket testing in schools, laboratories, factories and other social areas. Home improvement acceptance and safety inspection, saving you a lot of time testing socket problems.