Model "4381" SALES B KIT FOR PRODUCT CODE:MB4-AS07-18406000C; Pressure Reducing Regulator, Tfe Gasket/O-Ring; 1/2" Size; 316l SST Body & Cf3m SST Spring Chamber; S0 Trim: 316l SST Metal Seat,Tfe Coated 302SST Diaphragm; Opt-4: Stabilizer (Recommended For Gaseous Service Only); Opt-1+ 6: Differential Construction