Case of 24 Sta-rite Rs1-ds Water Filter Cartridges Remove Rust And Sediment Case of 24 RS1-DS Water Filter Cartridges Remove Rust And Sediment Use Inside Nos. U25; OB-1 Or OB-5 Filter Housings To Extend Life of Major Appliances Or Provide Clean; Fresh Drinking Water By Removing Sand; Silt; Rust And Loose Scale (20 Nominal Micron Rating). Pleated Resin Impregnated Cellulose Construction For Increased Efficiency. 5 GPM; 3-month/15;000-gallon Life Depending On Usage And Water Conditions.