We installed an Isotherm sea water cooled unit a few months ago - so far so good. We bought the 4203, which may be a discontinued model, as Isotherm was selling it on eBay. It is a holding plate system, medium sized plate, but the plate is cooled down to 0f, not 14 or 16 as usual with fridge systems. It is made to be a Freezer. The installation is as a spillover fridge, and other than coming to grips that we will need to rebuild our icebox, we have been happy with it so far.
Chris