This is NOT for installing an LED bulb in the older style Model S HID/Halogen projector headlights. These modules allow you to replace your entire HID/Halogen based headlights with the newer 2016.5-2021 Model S LED headlights. The newer headlights use LINBUS signals to function, the older cars only use basic 12v to power the headlights, DRLs, etc. These modules take the 12v outputs from the headlight connector and convert them into a usable LINBUS signal for the new headlights to work in older cars. Still very expensive for what it is imo.