MODEL "31-N" LOW PRESS REDUCING GAS SERVICE REG. GRAPHITE/NBR GASKET 2" BODY SIZE,NO.6 (0.375") ORIFICE; WCB BODY,SST LOWER CASE,WCB SPRING CHAMBER,ARRANGEMENT/POSITION 4, STANDARD CONSTRUCTION INCLUDES INTERNAL SENSING UNLESS OPTION - "ES" IS SPECIFIED; S50N TRIM: 316LSST INTERNALS,BUNA-N SEAT & DIAPHRAGM WITH REINFORCING CORE; OPT-30: 150 LB RAISED FACE FLANGES; 5.0-7.0" WC RANGE SPRING; PER SPQ NUMBER 55195 WITH NO PRESSURE BEARING PARTS FROM CHINA OR INDIA;