Engel, Whynter, ARB and National Luna all manufacture 12-volt refrigerator freezers. They produce a variety of models for different applications, including marine, RV, camping and tractor trailers in sizes from 14 quarts to 85 quarts.
The units generally accept multiple electrical inputs, including 12v, 24v and 110v. They also have true compressor refrigeration systems, which allow them to maintain temperature settings from 40 F to well below 0 F regardless of the ambient temperature. These models are much more expensive than the 12v thermoelectric cooler models produced by manufacturers such as Coleman. However, the thermoelectric model's cooling capacity is dictated by the ambient temperature around it and does not have the capability to keep food frozen in warm or hot environments.