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. For use with 3 and 4 quart modelsWith air ventFits models 703-733, B301A-B301B, 704, 744, B401A-B401BSealing ring fits around inside rim of cover and forms a pressure-tight seal between cover and body during cooking