The product is a set of 4 O2 oxygen sensors designed for vehicles such as Buick, Chevy, Cadillac, and GMC models from 2009 to 2017. These screw-in sensors come with a wire harness included for easy installation. The sensors are a direct fit and are placed in various locations on the vehicle, including the upper, lower, rear, left, front, and right sides. They are designed to provide accurate oxygen readings for optimal fuel efficiency and performance. REPLACES PART #S 250-24649 ; 234-4815 ; 12584050 ; 12612430 ; 126334061