The sealing ring fits around the inside rim of the cover and forms a pressure-tight seal between the cover and the body of the pressure cooker during cooking. This sealing ring will directly replace your existing ring. The kit includes the sealing ring and a replacement rubber over-pressure plug. For Presto 2.5 quart and 4 quart cast aluminum cookersFor use with model number 40, 103, 104, 204, 403, 404, A401, A403A (PCC4H), A403AD (PCD4)Sealing ring fits around inside rim of cover and forms a pressure-tight seal between cover and body during cooking