Model locomotives are replicas of full-sized trains. The word, locomotive, refers to an engine powered by steam, diesel, or electricity. Hornby model railways come in various modes, scales, and gauges, with locomotives to match. Of course, you could build a railway without locos, but where would the fun be in that? Scale refers to a model's size in relation to the real world. Gauge is the width of the track. The most popular combination in the UK is a 1:76 scale with 00 gauge locomotives. But be careful when making a purchase - you'll need to make sure both scale and gauge match your current layout. Our Hornby TT:120 range is much smaller than your typical model railway. 'TT' stands for tabletop, and '120' is the scale.