Designed in 1960 by the N&W as the H-11 class which is an enlarged PRR H-39 70 ton hopper. In 1964, the size was increased to 12' 3" high, cubic feet increased to 3433 and weight capacity increased to 90-100 tons. Over 130,000 have been built. Three distinctive characteristics highlight this class of hopper: roping eye with integral end buffers; end slope sheets are at a steeper angle than the hopper sheets; 13 riveted side posts with the middle two panels wider than the rest. Other features include; Wine door locks and full height side ladder stiles. Pullman, Greenville Steel Car, and Trinity built similar cars. The cars were built by PRR, B&O, C&O, N&W and RDG. Bethlehem Steel and ACF supplied prefabricated kits to other railroads.