Inside the 'box' it is a is a 'freezer', outside a 'refrigerator'. Our IsoTherm
unit is similar and is pre-charged. It is NOT rechargeable. To make it so would require soldering on a nipple, and that won't be cheap
. The box in the picture is the evaporator plate. Somewhere you will have a compressor. (Ours in in the port lazarette.) Our unit is dual voltage, can run on 110v when available or 12v when 100v is not available.