A Gaterunner, also known as a Gateformer, is placed into an unvulcanized rubber mold to form a large part of the gating system. Each Gaterunner has an integral center plug with a hemisphere that forms a dome in the center of the bottom half of a rubber mold. This dome enhances the speed with which molten metal is distributed throughout a rubber mold. Made of zinc, Gaterunners are available in 2 diameters. Made in USA.