Check the listing for details. TGI GTS-550 Compatible RO Filter Kit (Membrane Sold Separately). Condition: New. Listed at 50.96 USD. 1-Year Filter Replacement Kit for TGI GTS-550 Reverse Osmosis System (RO Membrane Sold Separately) High-quality compatible filter kit includes: * STAGE 1 - 1x Sediment Pre-Filter (93023) - Replace every 6-12 months or as needed * STAGE 2 - 1x Carbon Block Pre-Filter (OMB934-5M) - Replace every 6-12 months or as needed * STAGE 3 - 1x Carbon GAC Pre-Filter (OCB934RO T33) - Replace every 6-12 months or as needed * STAGE 4 - 0x (RO Membrane 655007-00 Sold Separately or with Replacement Kit YSM-TGIGTS550) - Replace every 24 months * STAGE 5 - 1x Inline Carbon Post Filter 2" x 10" (CL10ROT33-BB) - Replace every 6-12 months or as needed Filters may need to be replaced more often than indicated depending on incoming water contaminant levels and volume of water being treated.