The professional series Probe-Pro Tone Tracer traces non-active wiring when used with Toner-Pro Tone Generator (VDV500-063, sold separately). It features a responsive, durable, replaceable non-metallic, conductive tip and a work light for use in dark spaces. A headphone jack allows for headphone (not included) use in extreme noise environments. The terminal block confirms the toned pair has been located. 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.