The Realistic FM Signal Amplifier increase the sensitivity of the FM radio in your car, truck, or boat. It provides more than 10dB gain, which triples the strength of the input signal your radio receives. This aasures you a better signal and more reliable FM reception than you presently have. You can count on better performance in especially marginal areas. The unit operates with either negative or postive ground systems and uses so little current it can remain on all the time.