Ringfeder underrun protection devices can be selected from components or delivered as complete ready-to-mount systems. This makes ordering and mounting quick and convenient, saving time and hassle for the bodybuilder. The foldable protective beam can easily be folded out of the way when coupling a trailer to the truck. The smooth operation and ergonomic design make this manoeuvre quick with minimal effort for the driver. The protective beams are available as either circular tubes or open U-profiles. The open U-profile is ideal for mounting back lights in the beam, and such system is delivered with parallelogram.