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Model trains come in a variety of different sizes, called scales. The scale of a model railroad is it’s relative size in proportion to real-life trains. The distance between the rails is typically called the ‘gauge’.

T gauge is a model railway size with a track distance of 3 mm. It is the smallest commercial model train gauge in the world. For decades, the most common and popular scale is HO.

Here’s a short video explaining the differences.