I bought this used from another member about 2 years ago. I replaced the sediment filter about 6 months ago and the carbon filter when I bought the unit. It filters down to 6ppm before the DI resin. I added the extra DI canister. It will need the resin replaced. I can repack the DI if you want for an additional charge. This unit has dual RO membranes. Also has the dual TDS meter with back pressure gauge. I may have an extra sediment filter to throw in. $150 obo.