Compatible with select vehicles. Including: Buick, Cadillac, Chevrolet, GMC, Hummer, Isuzu, Oldsmobile, Pontiac, Saab, Saturn and Suzuki models for a precise fit. Retains warning chimes. To enable continued operation after your vehicle's amplified or non-amplified sound system has been removed or replaced. Also retains R.A.P. (Retained Accessory Power) in equipped vehicles. Compact design