Mirro 9890 Gasket Mirro, Mirro-Matic Cooker Gasket 9890 Mirro Pressure Cooker Seal/Gasket PN 9890, S9890, S 9890, 9890S, M9890. IN STOCK!! M9890$10.49 Order before 2:00 PM ET this item will ship same day. Orders placed after 2:00 PM will ship next business day! Soak gasket in hot water 10-15 minutes before using. Rinse and dry thoroughly. Any residue released from rubber is harmless. Lubricate gasket lightly with cooking oil or shortening the first 2 or 3 times only. See Pressure Cooker book for more detailed information. Remove from cooker after every use and wash in hot soapy water.