This type of container is capable of maintaining the temperature of the frozen, chilled or warm cargo.

A refrigeration unit is built onto the nose of the container and power is provided by a motor-generator (when a container is on wheels), by a terminal (when grounded in a yard) or by a ship (when laden on board).

Air, cold or warm, is supplied to the inside of a container via an air duct system that enters the container from the bottom. Air circulates under, over and through the load before it returns to the refrigeration unit. This circulation is repeated continuously when the unit is in operation.