In the 1930's ACF introduced a new covered hopper which would allow bulk shipments of dry materials. Previously these were packaged and resulted in hand loading and unloading. These commodities included cement dry chemicals, flour, grain. sand, sugar and many others. The first cars where shipped in October 1936 and had a capacity of 1958 cubic feet. These where soon to become a railroad standard and received AAR designation "LO". They were 35' 3" in length had 2 bays with 4 discharge openings, 8 square roof hatches and 70 ton weight capacity. Through the years they were copied by several other manufacturers with very few visible changes. In time many railroad purchased or leased these cars, including roads such as ACL, C&O, CB&Q, Clinchfield, DT&I Erie, Great Northern, Nickel Plate Road, N&W, Santa Fe and many others. Many private owner cars also existed. Between 1936 and 1957 more than 21,000 of the ACF designed cars were built some of which still can be found in company service on various roads.