Meter King MK-V1 Non Contact Voltage Tester, Circuit Tester with Flashlight & Audible Alert Our most popular electrical tester use our voltage tester pen to detect voltage in wires and standard U.S. outlets Every single meter king voltage detector has been inspected for quality control, ready to use out-of-the-box, just install included AAA batteries The meter king non contact voltage tester is trusted by handymen and home inspectors Hundreds of 5 star reviews: check out what hundreds of customers have to say about our voltage tester The pen makes an audible "beep" and the tip turns red when voltage between 50 and 1,000 AC is present