Check the listing for details. NorthStar RO Filter Set - Pre and Post Filters plus Membrane 7287506 and 7287514. Condition: New. Listed at 133.99 USD. NorthStar Reverse Osmosis Complete Filter Change Set - Pre and Post Filter Plus Membrane Set with Battery included and Bonus Filter Change Reminder Tag - part # 7287506 and 7287514Fits NorthStar Model NSRO42C4 RO SystemsManufacturer recommends changing pre, post filter set every 6 months and membrane every 1-3 years *** Please note that due to health and sanitation reasons we are unable to process returns on opened filter packages that don't fit your model. Please ensure that you're ordering correct filters for your system***NorthStar Reverse Osmosis Complete Filter Change Set - Pre and Post Filter Plus Membrane Set with Battery included and Bonus Filter Change Reminder Tag - part # 7287506 and 7287514Fits NorthStar Model NSRO42C4 RO SystemsManufacturer recommends changing pre, post filter set every 6 months and membrane every 1-3 years *** Please note that due to health and sanitation reasons we are unable to process returns on opened filter packages that don't fit your model. Please ensure that you're ordering correct filters for your system***