MODEL 120 -PISTON TYPE DIFFERENTIAL PRESSURE GAUGE WITH +/- 3-2-3% ACCURACY., 316 STAINLESS STEEL BODY AND INTERNALS WITH CERAMIC MAGNET, 4.5 INCH (114.3MM) UNIDIRECTIONAL DIAL WITH ENGINEERED PLASTIC HOUSING AND SHATTER RESISTANT LENS., BUNA-N SEALS, 1/4” FNPT BACK CONNECTIONS, REVERSED HIGH/LOW PROCESS CONNECTIONS; MAXIMUM INDICATOR FOLLOWER POINTER, LIQUID FILLED DIAL CHAMBER ( GLYCERIN)