Operating Era: 1910-1964. THIS SERIES NOW COMES WITH OUR ONE-PIECE ROOF FRAME. Baltimore & Ohio, Lehigh Valley. B&O settled on a standard house car in 1910. From then until 1924 all box cars were built to this design. However, over the years many improvements were made both in new cars and upgrades of older cars. The M-15/15A classes were completely double sheathed double door cars. All later designs had single doors. The M-15B/C/E designs had reverse corrugation 3-panel ends. The M-15D had alternate USRA steel ends. The M-15F and M-15H/J rebuilds had single sheathed "Indestructible" ends. Almost all classes had some physical differences despite the similarity of ends. The cars went through at least 5 changes of lettering, ending up with the billboard B&O. M-15B-J cars ran into the late 1940`s before scrapping started and some lasted into the 1960`s. We model the M15, M15A, M-15B, M-15C, M15D, -E and -H classes in physically different kits with decals that cover from delivery up to, but not including billboards.