FEATURES * 1/8 MPT * Brass body * Cracking Pressure: 40 PSI * Includes rubber Washer (Safeety Valve) (RPI Part #MIW123) * See NOTES below for Serial #'s this part fits FITS: Chamber MODEL(S) THIS PART FITS: M11, M11D, M9, M9D NOTES: CHECK SERIAL NUMBERS HERE: FITS M9 -020 thru -022 with Serial # V721881 thru present. FITS M9D -020 thru -022 with Serial # V721881 thru present. FITS M11 -020 thru -022 with Serial # V721881 thru present. FITS M11D -020 thru -022 with Serial # V721881 thru present.