The Watts Premier WP105321 UF-3 Membrane Filter is a push button ultra filtration (UF) membrane filter designed for the UF3 Pure Filtration System. This UF membrane filter effectively reduces sediment and suspended particles, as well as removing cryptosporidium, toxoplasma, giardia, and entamoeba from drinking water while allowing beneficial minerals through. Filter maintenance is easy with the unique swivel-valve, push-button assembly that allows for a one-step filter changes that doesn't require shutting off the water source.