Reefer Containers, also known as refrigerated containers, are specially built containers used to carry perishable items such as fruits, vegetables, fish, meat, and so on, as well as pharmaceutical supplies. These products are refrigerated or frozen to keep them fresh throughout transit.

Fruits and vegetables, meat, fish (fresh or frozen), milk and dairy products, flowers, medications, juice and concentrate, and chocolate are all frequently carried in reefer containers. When shipping reefer cargo, four factors must be considered: temperature, ventilation, humidity, and drainage.

All typical reefer containers are designed to keep chilled and frozen goods at temperatures ranging from +25° C to -25° C. A portion of the worldwide reefer fleet is also capable of holding temperatures as low as -35° C. Special containers (super freezers) can keep temperatures as low as -70° C.

Refrigeration containers require an electrical connection. This source could be a tank, a terminal, a ship, or a generating set. A microprocessor, which serves as the electronic temperature recorder, is housed within the container. This device records all data, including supply and return air temperatures, remote load probe temperatures, defrost activities, set point changes, on/off time, and so on. Load probes can be used to record the temperature of individual shipments. These probes are cables with a temperature sensor attached to one end.