From Chevrolet the DRL lights only come on during the day time, this harness allows the lights to stay on with the headlights which helps night time vision. It is also needed when upgrading your DRL to LED. We offer the harness by itself or you can add it to your order when purchasing LED bulbs. Will not work correctly on non-RS Camaros, 2014-15 Camaros or ZL1 Camaros. Only one needed per car.