Metra Electronics LC-GMRC-04 Custom Fit Data Bus Interface Incl.: LC-GMRC-04 Interface/LC-GMRC-04 Harness Custom Fit Data Bus Interface Provides accessory (12V 10A) Retains RAP Provides NAV outputs (parking brake/reverse/speed sense) Used in nonamplified models or when bypassing a factory ampl Used in models without OnStar(R)