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. When installing a sealing ring, work it into the cover in four small sections, for example, top, bottom , left and right. Work it into the groove a small section at a time until it is fully in place. Place the cover on the cooker body. Put one hand on the top center of the cover and push down firmly. Open and close the cover several times. Fits Presto Pressure Cooker models: 01/PCC4, 01/PCC4A, 01/PCC4D, 01/PCC4H, 01/PCD4, 01/PCD4H, 01/PCE4, 01/PCE4A, 01/PCE4H, 103, 104, 204, 40 (2 1/2qt), 40 (4-qt), 403, 404, A401, A403A, A403AD, A403AT, A409, A410A, A411A, A412A, A413A, A414A, A415A, A416A, KE02A, KE02AT, PB01A, PB05A, PB07A.