Open-air merchandisers keep products chilled using a directed flow of air – also known as an air curtain – that separates ambient temperatures from food and beverages inside the machine. Because of their design, Open Air Merchandisers operating with an air curtain are less energy efficient than ones with traditional glass doors, but in many cases, the higher operating costs are more than recovered in additional sales. The perfect spot for an open-display refrigerator is indoors near an area with lots of foot traffic. Many operators choose to install an open cooler near ordering and checkout stations, since consumers are more likely to stop and peruse products when they're already stuck standing in line.