It may be wrong, but starting years ago, I installed the original euro H1 lights without a gasket on my 70 911. I only had the thick rubber gaskets to work with, and there was no way the light was going on the fenders. (both fenders OEM replacements with little paint, etc). However, the lights pretty much snap onto the outer mounting brackets (starting with the top one), and the retaing screw in the bottom holds the assembly in very nicely. Lights don't move, rattle, or mar the paint in any way. And they have never fallen off on me.