Cars and Trucks:  If you aren't sure what model light fits your automobile, Here is a common lookup tool.

RVs: There are no mass lists for RVs like cars, and when you can find a list from the RV manufacturer or off the Internet,  they are often inaccurate. Look at the back of your current bulbs for a number that starts with an H or a 9000 series number, those can be matched to the headlights on our website. You also have to look to ensure you have a clear open air 2” x 2” area directly behind your bulb to accommodate the LED heat sink.

If you have Daytime Running Lights (DRL), or otherwise computer controlled headlights, they may not be LED compatible.  On some vehicles, the DRL send a lower voltage to the headlamps to make them glow.  LEDs do not work at lower voltages, so in DRL mode they cannot come on, flicker, or present an error on the dash.  The work around is to disable the DRL or keep the headlight switch "On" during the day.