This power supply noise suppression device can help eliminate the most common power-related electronic noise problems associated with car audio systems,such as background noise or alternator whine.It is designed for installation into the engine compartment at the alternator. - 12Volt DC. - 40Amp nominal,70Amp maximum. - 72MM L x 40MM dia - Red w/ ring terminal - positive input. - Blue - ground - Red w/ butt connector - positive output. P.S.:Can not work with 6V System.