This could be the fix for fog lights ebing cracked by rocks.

http://www.xpel.com/bulk.html Last peoduct. 40 mil clear film to prevent rock chips. This could work...

Here's a review of it on a porsche... I don't think it'll take nearly as long on a 4 inc light as it did on compund curves.

 

Someone said the heat from the light busts them also.. Don't know have never cracked one yet......

PEaCE...................

 

Don't know if this qualifies me as an expert on fog lamps cracking...but

Iam on my 3rd set of replacements because of cracks and there is never an impact on the lense. It seems to be heat related. All my replacements have been covered under warranty. knocking on wood
On a side note, I have a crack in one of the ones in my truck after the Florida trip. If we get a couple of nice days, I'll drive to the dealer and see if set #4 are in my future