A refrigerator truck is a van or truck designed to carry perishable freight at specific low temperatures. Like Refrigerator cars, refrigerated trucks differ from simple insulated and ventilated vans (commonly used for transporting fruit), neither of which are fitted with cooling apparatus. Refrigerator trucks can be ice-cooled, be equipped with any one of a variety of mechanical refrigeration systems powered by small displacement diesel engines, or utilize carbon dioxide (either as dry ice, or in liquid form) as a cooling agent.