Brand new design out of our shop! Some type of check valve or overflow line is mandatory on the majority of race car classes. Unfortunately , there are not really any pieces that are not bulky, ugly, and in the way. We have come up with a solution for that! Our check valve is designed to be screwed into our overflow bung on a fuel cell, and stays nice and low to the top of the cell. Machined out of high strength aluminum, this piece is a great investment that will not break the bank!