DualCheck Non-Contact Voltage Tester & GCFI Outlet Tester, GFCI Outlet Tester On 1 End & A 50-1000V AC Non-Contact Voltage Tester On The Other, Quickly Provides An Accurate Analysis Of Any 120V Receptacle, Detects 50-1,000V AC, Bright 360 Degree LED Visual Indicator Along With An Audible Beeping Indicator Of The Presence Of Voltage, Precisely Detects The Required Low Resistance Values, Less Than 10 Ohms, On Ground Wire Instantly & Features A Clear & Easy To Understand Single LED Read Out Indicating Correct Wiring Or Bad Ground.