Three Stage Water Filter System One year Refill Cartridge Kit 2 PP Sediments, 1 GAC Filter, 1 BAC Filter Fits Standard 10″ x 2.5″ Housings This is a replacement filter kit for 10″ standard three stage water filter systems. It includes all the filters that need to be changed regularly on the unit. Filters should be changed on your unit every 6-12 months depending on usage and water quality. We recommend changing them at least once a year to ensure the quality of your water. 2 x PP SEDIMENT Filters: To remove sand, silt, dirt and rust particles in water. Filtration Precision: 1 micron Replace it every 3-5 months 1 x GRANULAR ACTIVATED CARBON (GAC) Filter: To adsorb the chlorine, organic matter, odor, smell turbidity Filtration Precision: 5 micron Replace it every 6-12 months 1 x BLOCK ACTIVATED CARBON Filter: To adsorb the chlorine, organic matter, odor, smell turbidity, and suspending particles. Filtration Precision: 1 micron Replace every 6-12 months. Payment: Payment Methods: PayPal (Preferred) Shipping: This item ship by USPS Priority Mail. Usually 1 – 3 business day delivery.