Check the listing for details. WaterGeneral FK-4 RO system Replacement Filter Kit RO585 RD106 Genuine Original. Condition: New. Listed at 45.00 USD. Replacement filter kit, high capacity, replace every 12 month, Part no. FK-4 FK-4 is for WaterGeneral Model: RO585, RO6100+DI, and RD-106 systems To view a list of replacement filters for WaterGeneral systems, visit FilterDirect.com and click on Replacement Filters and select your model name. (For other brands and models like Honeywell RO9100, FilterCold RO5, or Aquasafe systems, part no. is different. Please email us first or visit our website: FILTERDIRECT.COM to view a list of replacement filters for other brands RO system) 1st stage: high capacity, 5 micron sediment filter, to remove sediment, rust, sand, (replace every 12 months) 2nd stage: high capacity carbon filter, carbon block, coconut shell activated carbon removes chlorine, taste & odor (replace every 12 months) *We have modified the filter from granular to carbon block for higher performance. 3rd stage: high capacity carbon filter, carbon block, coconut shell activated carbon further removing chlorine to ensure 100% removal of chlorine (replace every 12 months) *We have modified the filter from granular to carbon block for higher performance. NOT INCLUDED: 4th stage: HTFC-75 or HTFC-100 Premium membrane we use genuine Filmtec membrane material, 100 gal/day, it removes 95% to 98% of all chemical, dissolved solids in tap water. (replace every 2-3 years) Membranes are also available from our Ebay Store. 5th or 6th stage: high capacity final stage inline carbon filter, granular activated carbon, to improve taste of water. (replace every 12 months)