This connector allows side-by-side connection or "horizontal stacking" of radiators from the airplex modularity system. The connector is made from nickel plated brass and equipped with two O-ring gaskets. The connector can be inserted into the connection openings on the radiators without the need for tools. It is secured by being screwed to the radiator with separately available connection plates (not included). The radiators are connected flush to each other with this system. By connecting multiple radiators, a multitude of configurations and sizes can be realized.