Common Mode Filtercord for CB and Mobile Electronics, Input 6 - 16 VDC, Up to 20A, Connector Uniden/President T-3. 
All noise or interference enters a 2-way radio thru the antenna system or the 12 volt DC lines.

The XLF-20C™ XLF-20M™ are rated at: 6-16 Volts DC 20 amps continuously, and are known as COMMONMODE filters. Unlike the PLF the XLFs address a WIDER range of interference problems and will reduce or eliminate not only DC noisewhich include alternator, turn signals and windshield wipers, it will also cancel any RFI that is coupled into the DC line, and due to its design there is absolutly no voltage drop thru the filter. In addition the commonmode filter provides the highest isolation to both RF and Noise.
Commonmode filters will reduce or eliminate noises in all 12 volt electronic components, these include 2 way radios, audio systems, including AM/FM receivers, stereos, amplifiers and video components.
The instructions on the backer card now give instructions for a simple test that will determine if the noise/interference is thru the Antenna or DC lines.