The Presto 09907 Sealing Ring & Automatic Air Vent is compatible with a wide range of Presto pressure canners, including models 7, 7S, 7AV, 7B, CA16, CA16H, 01/CA16H, 01/CA16A, 21, 21S, 21AV, 21B, CA21, CA16H 01/CA21H, and CA21H. It fits both 16-quart and 21-quart canners.