The Monoprice 3-In-1 Tracer/Toner/Cable Tester Is A Professional Tool Used To Test And Troubleshoot Rj45, Rj11, And Bnc Cables It Can Also Be Used To Trace And Identify Individual Wires Within A Wire Bundle Or Group And Can Provide Talk Testing Functionality Between Telephone Units The Tester Is Composed Of Two Main Units: The Tone Generator/Cable Tester And The Amplifier Probe With Sensing Tip Each Unit Is Constructed Of Plastic With The Edges Covered In Rubber To Improve Grip