Reefer trailers are slang terms for refrigerated containers. These refrigerated trailers have insulated walls and self-powered refrigeration units. Reefers are commonly used to transport food and other temperature-sensitive goods. Trailer is a type of cargo Trailer that is pulled by a car or truck. A reefer trailer has a build in cooling system that helps maintain the correct temperatures for perishable items. When Trailer first became popular in the early 1900s, they were used to move perishable foods such as dairy, meat, and vegetables. Today, reefer trailers are still used to transport food, but they are also used to transport flowers, medicine, and other items that require temperate conditions. Reefers are come in different sizes, the most common being the 53-foot Trailer. Reefer trailers can be either single or multi-temp, meaning that they can maintain more than one temperature at a time. Multi-temp reefers are typically used to transport products that have different storage requirements, such as ice cream and chocolates.