These fender braces are used at the rear of the fenders (just in front of the doors) to help stabilize the shape and position of this area.
I've found that particularly for customers who are building cars that are pure race car (i.e., will see some, or mostly, street use), this seems to be an area where a fair amount of labor is required to accomplish the same objectives served by fairly simple fiberglass parts.
These fiberglass braces are molded right off the factory fenders, where the metal braces are an integral panel in the sheet metal assembly.
$90.00