SWITCH, DIFF, PRESSURE, MODEL: 138-G2-M4-FI1A-PP. RANGE: 15-PSIOVERRANGE: 1000PS1, PROOF: 2500PSI,13=NO. 13PISTON, S=EXPLOSION PROOF HOUSING CLASS, GROUPS C &D,DIV.1&2-3/4”NPT(F)CONDUIT CAST IRON, G=SPDT,DEAD BAND FIXED,, RATING: 15A,250VAC,5A125VDC, 2=NO. 2SPRING, M4=316LSS DIAPHRAGM/VITON O-RING, F=CBS PROCESS CONNECTION 1A=1/4”NPT(F), PP=PAPER TAG., MFR:STATIC ”O”RING,PRESS.SWIHCH CO., #13S-G2-M4-F1A-PP