OEM Xenon headlight ballasts and a D3S bulb (4300K Kelvin Scale). These are used as H.I.D. (High-Intensity Discharge) projection-type Xenon headlights and powers D3S Xenon bulbs.
If your Tesla is showing a headlight out, and you can manually reset the headlights and it turns back on, then this is probably the issue.
Sometimes you can get away with just replacing the bulb, if you want to give that a try select just bulb and come get the ballast if you need it!