For the do-it-yourselfer, Dometic offers the CoolMatic and Adler/Barbour ColdMachine series of condensing units and evaporators designed for easy installation.
The Grunert PassageMaker Series of condensing units can cool one or multiple boxes.
The KRA Series of cabinet condensing units is designed for use with cockpit freezers/refrigerators, catch-box chillers, or built-in galley freezers/refrigerators.