Check the listing for details. PuROTwist 4000 RO Filter Replacement Kit with 75 GPD Membrane. Condition: New. Listed at 169.68 USD. 1-Year Filter Replacement Kit for PuROTwist 4000 with 50 GPD TFC Reverse Osmosis Membrane and FREE Replacement O-Rings INCLUDES: * STAGE 1 - 1x Sediment Pre-Filter (Q5605) - Replace every 6-12 months or as needed * STAGE 2 - 1x Carbon GAC Pre-Filter (Q5629) - Replace every 6-12 months or as needed * STAGE 3 - 1x RO Membrane TFC 50 GPD (TQ56-75-XHR-FC200) - Replace every 24 months * STAGE 4 - 1x Carbon GAC Post Filter (Q5633) - Replace every 6-12 months or as needed * O-RINGS - FREE Replacement O-rings for Filter Heads (4x H-118 and 4x H-011) To order this filter kit without the RO membrane, order item YS-PURO4T75 *Filters may need to be replaced more often than indicated depending on incoming water contaminant level and volume of water being treated.