Best of the best in ro/di systems. Has two ro membranes that were replaced recently. Three stages of prefilters which are also newer. The di resin section has a cation, anion, and mixed resin chambers individually. The resins will need to be replaced. Previous owner said one of the canister had a small leak at the gasket area that might be fixed with new oring seals. It also has a 3 way tds meter to monitor the di resins. Visit my table at coralbeauties to pick up this item