REPLACEMENT STAGE 1 FILTER IS AMAZON ASIN B01NCZ7452. COPY AND PASTE ASIN TO YOUR AMAZON SEARCH BAR.>>>>> PLEASE NOTE: THE ABSOLUTE BEST WAY TO SEPARATE WATER FROM YOUR COMPRESSED AIR LINES STARTS WITH THE COMPRESSED AIR LINES THEMSELVES. ALWAYS FORCE AIR TO CLIMB VERTICALLY WHILE POOLING WATER IS CARRIED DOWNWARDS BY GRAVITY. USUALLY INTO SOME SORT OF DRAIN OR BALL VALVE THAT IS DRAINED OUT PERIODICALLY. COMPRESSED AIR DRYERS REDUCE THE QUANTITY OF WATER VAPOR, LIQUID WATER, HYDROCARBON, AND HYDROCARBON VAPOR IN COMPRESSED AIR. MOISTURE IN COMPRESSED AIR IS HARMFUL. WATER DAMAGES A COMPRESSED AIR SYSTEM SEVERAL WAYS. THE RESULT IS LOWER PRODUCTIVITY, INCREASED MAINTENANCE, AND HIGHER OPERATING COSTS. YOU CAN MINIMIZE THE DAMAGE WET COMPRESSED AIR CAN INFLICT ON YOUR SYSTEM BY DRYING IT.