ACF introduced the 5250 cubic foot size covered hopper in 1964, and has since built neaerly 20,000 cars. Most of the cars were equipped with pneumatic outlets and eight 20" round hatches for use in transporting plastic pellets. In addition to the plastics cars, a number have been built or converted with gravity outlets and elongated hatches for grain type products. As with most things with long production spans, the design has evolved with changes in the physical features of the body and fixtures. The Atlas model features three unique body style variations to represent those changes from the 1960s into the 21st Century.