A refrigerated container or reefer is a shipping container used in transportation of temperature sensitive cargo. While a reefer will have an integral refrigeration unit, they rely on external power, from electrical power points (“reefer points”) at a land based site, or a container ship. When being transported over the road on a trailer or over rail wagon, they can be powered from diesel powered generators (“gen-sets”) which attach to the container whilst on road journeys. Refrigerated containers are capable of controlling temperature ranging from -30 degrees up to 30 degrees. There are Twenty foot and forty foot reefers available.