The Metra XSVI-2004 is designed to provide a 12 volt 10 amp switched accessory output along with the rest of the wires needed to install an aftermarket radio. The R.A.P. (Retained Accessory Power) function, where power is supplied to the radio after the ignition is shut off until one of the doors are opened, is retained by the XSVI-2004. The XSVI-2004 will also retain the amplified door woofers through the use of a differential line converter. This helps eliminate turn on/off pops and allows the user to adjust the level of the door woofers.