THIS IS A HIGH QUALITY GLYCERIN FILLED PRESSURE GAUGE. RATED WOG (WATER, OIL AND GAS) GLYCERIN FILLED GAUGES HELP DAMPEN THE EFFECTS OF PULSATION AND VIBRATION CREATED BY YOUR MACHINE OR EQUIPMENT. THIS ALLOWS FOR A MORE ACCURATE GAUGE READING OF PRESSURE. GAUGE ALSO PERPETUALLY LUBRICATES THE MOVEMENT AND KEEPS THE CONTAMINATES SUCH AS DIRT AWAY FROM ALL MOVING PARTS, WHICH IN TURN, EXTENDS THE LIFE OF THE GAUGE. THIS GAUGE IS SPECIFICALLY DESIGNED FOR HYDRAULIC AND PNEUMATIC APPLICATIONS AS WELL AS ANY COMMERCIAL OR INDUSTRIAL APPLICATION NOT CORROSIVE TO BRASS AND BRONZE PARTS WHERE GLYCERIN FILLING IS SUITABLE FOR USE. Note: THIS GAUGE IS NOT RATED FOR POTABLE WATER APPLICATIONS.