Thanks to the Car-Builders Association, By the early years of the 20th century the interior dimensions of the box cars and become standardized, with the interior of the length of 36 feet. Cars were wood framed covered with wood siding, steel underframes, with either straight or deep "fishbelly" sills had replaced wood and steel was beginning to be used for roof and ends. Our kit models what has become the most common boxcar of the Roarin' 20s, with cars remaining in the service through the end of WWII and in company service for years after.