Boss Audio Systems CAP3.5-BRS is a 3.5 Farad stiffening capacitor designed to supplement your car's charging system when your audio amplifier places a high current demand on it. It features a digital voltage display, reverse polarity protection, and a built-in relay system that disables the capacitor and triggers a buzzer if the polarity of the connections is reversed. The CAP3.5-BRS is easy to install and comes with all the necessary hardware, including mounting brackets and a charging/discharging resistor.