SPUN FILTER IS MADE OF FINE MELTED POLYPROPYLENE, WHICH IS BLOWN AND SPUN IN A CYLINDER LIKE FORM. • 5 MICRON SPUN FILTER FOR RO WATER PURIFIER REMOVES ALL SEDIMENTS, VISIBLE PARTICLES , SAND , RUST , DIRT AND MUCK DOWN TO 1 MICRON . • THESE FILTERS HAVE GRADED DENSITY LAYERS, MEANING THE OUTER LAYERS ARE MORE POROUS, CATCHING LARGER PARTICLES, WHILE THE INNER LAYERS ARE A FINER MICRON CATCHING SMALLER PARTICLES. PP SPUN FILTERS ARE MANUFACTURED OF THERMALLY BONDED POLYPROPYLENE MICROFIBER TO ENSURE HIGH EFFICIENCY. THERMALLY BONDED MICROFIBER HAS MINIMAL FIBER RELEASE AND CONSISTENT FLOW RATE. THEY ARE IDEAL FOR FOOD AND BEVERAGE APPLICATION AS THEY DON'T IMPACT COLOR , TASTE OR ODOR OF THE LIQUID BEING FILTERED.