REPLACEMENT FILTERS CAN BE FOUND ON AMAZON. ASIN B01MTC8AAH. COPY PASTE ASIN TO YOUR AMAZON SEARCH BAR. THIS UNIT WILL ALLOW YOU TO REGULATE THE FLOW OF AIR ON YOUR COMPRESSED AIR LINES WHILE SIMULTANEOUSLY REMOVING THE EXCESS MOISTURE BEFORE REACHING YOUR PNEUMATIC TOOLS. THIS TYPE OF REGULATOR ONLY REGULATES AIR FLOW, NOT LIQUIDS. THIS UNIT COMES WITH 1 BACK MOUNT GAUGE AND HAS 2 GAUGE PORTS. EACH PORT LOCATED ON FRONT AND BACK OF REGULATOR IF YOUR APPLICATION REQUIRES A DIFFERENT DIRECTION OF AIR FLOW. THIS FILTER/REGULATOR IS CLEARLY MARKED FOR DIRECTIONAL AIR FLOW. THE INLET IS MARKED "IN". THE OUTLET IS MARKED "OUT". AS AN ADDED SAFETY FEATURE, YOU CAN REMOVE THE REGULATOR KNOB TO PREVENT UNWANTED TAMPERING OF THE UNIT. THIS UNIT HAS A SEMI AUTOMATIC DRAIN THAT ACTS LIKE AN OVERNIGHT DRAIN. WHEN PRESSURE IS APPLIED TO THE BOWL, THE DRAIN WILL HOLD THE MOISTURE CONTENTS UNLESS YOU MANUALLY DISCHARGE IT. WHEN NO PRESSURE IS APPLIED TO THE BOWL, THE DRAIN AUTOMATICALLY OPENS TO RELEASE THE MOISTURE. IF YOU REMOVE THE BOWL FROM THE UNIT AND DO A WATER TEST TO SEE IF HOLDS MOISTURE, THE BOWL WILL LEAK. THAT IS WHAT ITS DESIGNED TO DO. WHEN PRESSURE IS APPLIED, THE BOWL WILL HOLD MOISTURE CONTENTS AND PRESSURE.