The Klein Tools VDV500-820 Tone and Probe Pro Kit is a reliable and efficient electrical wire tracing tester. This top-of-the-line kit is perfect for testing RJ11 and RJ45 cables, and it comes with a variety of features that guarantee accuracy and precision. The VDV500-820 model is designed to meet the needs of professionals in the business and industrial industries, delivering high-quality results every time.