The pressure regulator for your pressure canner rests on the vent pipe, which allows excess pressure to be released. Compatible Products 21-quart Pressure Canner 21 21-quart Pressure Canner 21AV 21-quart Pressure Canner 21S 16-quart Pressure Canner 7 16-quart Pressure Canner 7AV 16-quart Pressure Canner 7S