A reefer trailer, also known as a refrigerated trailer or a refrigerated truck, is a type of trailer or truck that is equipped with a refrigeration unit that allows for the transportation of temperature-sensitive cargo, such as perishable food items, pharmaceuticals, and chemicals. The refrigeration unit can be powered by either an electric generator or by the truck's engine. The temperature inside the trailer can be controlled and monitored to ensure that the cargo remains at the correct temperature throughout the entire transportation process. This type of trailer is commonly used in the food and pharmaceutical industries for the transportation of goods that require a specific temperature range to maintain their quality and safety.