Made by ACDelco (OE), these sensors are bolt-on style and come in a set of four. They are OE/OEM part numbers 13545366 and 86803857, with interchange part numbers 13545366 and 84152501. The sensors are specifically designed for rear, front, left, and right placement on the vehicle, providing accurate tire pressure monitoring for improved safety and performance on the road. This comes as a package of 4 total new oem GM sensors.