Presto 09906 Pressure Cooker Sealing Ring/Automatic Air Vent Pack (4 & 6 Quart) Includes Automatic Air Vent. Replaces Presto part 33020. Fits Presto Pressure Cooker models: 01/PCS4, 01/PCS6, 02/PCS4, 02/PCS6, 803B, 804, 804B, 833, C301A, C301B, C401A, C401B, C601A, C603A