Model DA5 Rev E Back Pressure Regulator; 4" Line Size; Sales Kit A; Stainless Steel Body With Stainless Steel Spring Chamber; NT NACE Trim, CTFE Seat, BUNA-N Diaphragm, PTFE Static Seal, Elgiloy/PTFE U-Cup Dynamic Seal; OPT-40: Construction Per NACE Standard MR0175