Provides accessory power (12-volt 10-amp) Retains R.A.P. (Retained Accessory Power) Used in non-amplified systems or when replacing amplified systems Retains chimes Provides NAV outputs (parking brake, reverse, mute and speed sense) Retains OnStar®/OE Bluetooth® Adjustable gain control for chimes and OnStar® High-level speaker input Retains balance and fade Micro-B USB updatable