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. The following used these hoppers: B&O, Blue Diamond Mining, BN, C&I, C&O, CONRAIL, CHESSIE SYSTEM (B&O), CHESSIE SYSTEM (C&O), CHESSIE SYSTEM (WM), CHESSIE SYSTEM (CSXT), CHESSIE SYSTEM (CSX), Dayton Power & Light, D&H, D&RGW, Island Creek Coal, Intsel Corp, ITEL, LEF & C, L&N, LRWN, MKT, Missouri Public Service, MSDR, NORFOLK SOUTHERN, N&W, NP, NS, P&LE, P&S, Potomic Electric Power Co, PENN CENTRAL, Penna Power & Light, PRR, PVAL, READING, ROCK ISLAND, SANTA FE, SEABOARD, SLSF (FRISCO), SOO, SOUTHERN PACIFIC, TWRY, UMP, UMPX, UNION PACIFIC, UPPER MARION AND PLYMOUTH and WESTERN MARYLAND.