I have a kent marine 50gpd ro unit. there is a spare canister, tubing and fittings to add a DI section. this is a 3 stage RO unit. one for prefilter, one for carbon block and one for RO membrane. in great shape, and about half the life still in the filters. also have a new prefilter to throw in. i switched over to fowlr, so i don't really need the unit anymore. asking for $50.