In 1942 the War Production Board authorized the design of seven standard freight cars that utilized "composite" construction with wood replacing sheet steel wherever feasible. Saving approximately 2-1/2 tons of steel when compared to all-steel construction, the war emergency hopper was one of the successful designs. Over 11,000 of these hoppers were constructed from 1942 through 1945 and many remained in service either in original form or rebuilt with steel sides, throughout the 1950s and 1960s. Cars feature separately applied grab irons, realistic wood siding and operate on O-27 curves.