Before HO scale became the standard for model railroading, O scale was the dominant size, with a ratio of 1:48. However, in the early 20th century, a growing demand for more compact model trains ...

The gauge of an O scale train is 1.25 inches or 1¼ inches. The most popular train sizes are O scale and HO scale – HO stands for “half-O”. Lionel specializes in O scale trains.