Complete replacement filter set ONLY for APEC ROES-PHUV75 with serial number AZ-PHUV-3000 and above Pre-filter set lasts over 6 months for high performance contaminant removal; the TFC membrane and post carbon filter last 2-4 years Pre-filter set lasts over 6 months for high performance contaminant removal; the TFC membrane and post carbon filter last 2-4 years The 5th stage continuous UV sanitization destroys bac., vir. and cysts for chemical-free purified drinking water 100% US-Made high purity calcium carbonate filter effectively neutralizes acidity and raise pH in the water to enhance water taste for people who desire alkaline water