Abstract: In bottle top molds a plug is used as a closure for the opening in the top wall of the molds through which the molten metal is poured. The surface of the opening tends to become eroded by the molten metal flowing into the mold and, as a result, the plug no longer forms an effective closure rendering the mold unusable. To prolong the useful life of the mold, a ring-shaped member is secured to the top wall of the mold in register with the opening and covering the eroded surface. The ring-shaped member is configured to receive the plug so that it continues to form a closure for the mold.