Professional cable tester. Test cables with many different connector types: 3.5mm & 6.35mm MONO / TRS - 3 pins balanced XLR (M/F) - Phono/RCA - 2P, 4P & 8 P Speakon - RJ45 - 8 Pin mini DIN - S/Video - USB A/USB B - Midi. LEDs confi rm correct connections between the connectors. It works with 2x1,5V battery not included.