AlcaPure Edition Replacement filter 2-year bundle for Zero Installation Purifier Countertop Reverse Osmosis System: FIRST STAGE FILTRATION: 2 pieces 5-micron Prefilter removes Sediment, Rust, and other large particles. Replace every 12 months or as needed. SECOND STAGE FILTRATION: 2 pieces Carbon Block Filter removes Chlorine and other Disinfection by-products. NEW Option for Anti-Scale Carbon Prefilter. Use the Anti-Scale bundle option only when experiencing a short reverse osmosis membrane lifespan (under two years). NOTE: A brand new reverse osmosis membrane is also required when switching to the Anti-Scale bundle. Replace every 12 months or as needed. THIRD STAGE PURIFICATION: 1 piece 75 Gallon Per Day Reverse Osmosis Membrane. This element needs to be replaced only every 2 - 4 years, or as needed. FOURTH STAGE AlcaPure ALKALINE POST FILTER: 2 pieces Polishing Alkaline Post Filter returns beneficial minerals – Calcium and Magnesium to purified water for the best taste. It also increases the alkalinity of the water to a healthy level of 7-8 pH. Replace every 12 months or as needed. Note: If converting from OnliPure Edition to AlcaPure Edition by using this filter bundle, then smaller attachment clips are required. To reset the filter change indicator (Blinking Red Light), press and hold the “push" button for 5 seconds. To reset the reverse osmosis membrane replacement indicator (Solid Red Light) unplug the power supply from the back of the unit and plug it back in while pressing and holding the "push" button. Reverse Osmosis Membrane replacement step-by-step video instructions: