When you install your radio antenna (CB or 2-meter) you will need to test it for SWR (Standing Wave Ratio). I won't go into the explanation of SWR here, but to measure it, you will need to hook a SWR Meter up to your radio via the antenna cable. I installed a short jumper cable to the back of my radios, and connected the jumper cable to the antenna coax cable using a PL-259 barrel connector. This allows the antenna cable to be easily disconnected so the meter can be installed in-line without having to access the back of the radio, which can be a big hassle for one mounted in the dashboard or a console. You should be able to get these items at your local CB or HAM radio shop. I got mine from Firestik (you should be able to order through any Firestik dealer.)