Check the listing for details. RainSoft UF50 Compatible RO Filter Kit (Membrane Sold Separately). Condition: New. Listed at 27.98 USD. High-quality filter replacement kit compatible with RainSoft UF50 Reverse Osmosis System (RO Membrane Sold Separately) INCLUDES: * STAGE 1 - 1x Carbon Block Pre Filter (OMB934-5M) - Replace every 6-12 months or as needed * STAGE 2 - 0x (RO Membrane TFC-RS9-50 Sold Separately or Included with Replacement Kit YSM-RSUF50) - Replace every 24 months * STAGE 3 - 1x Carbon Block Post Filter (OMB934-5M) - Replace every 6-12 months or as needed Note: If your Rainsoft reverse osmosis system is from 2013 or newer, it most likely is the Ultrefiner II. The Ultrefiner II requires proprietary filters that must be purchased from a Rainsoft dealer. Conversion kits to generic non-OEM replacement filters are available. Filters may need to be replaced more often than indicated depending on incoming water contaminant levels and volume of water being treated.