Klein Tools Non-Contact Voltage Tester detects standard voltage in cables, cords, circuit breakers, lighting fixtures, switches, non tamper-resistant outlets and wires. A bright green LED indicates the tester is powered on. It changes to red and an audible tone sounds when voltage is detected. For more than 160 years, Klein Tools has manufactured premium-quality, professional-grade hand tools that deliver the performance, durability and precision needed to get the job done right. Our family of engineers, workers and craftsman continue to put six generations of expertise into every tool we create by using only the highest quality materials, superior workmanship, and keeping manufacturing as close to home as we can. Klein isn't just the name of our company, it's also our family name. And since we're an American company that's family-owned and family-run, you know you can count on us to be here tomorrow. Klein Tools doesn't just make great products, we make great products that stand up to the demands of the professionals who use them every day ... Since 1857.