O Scale Name originally was '0' (zero), '1' through '6' were already in use for larger scales. In the U.S., this is frequently considered a 'toy train' scale rather than for scale modelers. However, though toy trains use this gauge, they are often nowhere near scale. Scale modellers have begun to use this gauge for their scale models, resulting in a two separate groups of modelers within this "scale": "hi-railers", those who run toy train equipment on oversized track and scale modelers, who run scale equipment on scale track. A limited few have been able to combine both. Nowadays, even high-railers have the option of extremely precise scale models and track. Lionel, MTH Electric Trains, and Atlas O are major manufacturers of this scale. The best-known brand in Great Britain was that of Bassett-Lowke until the firm first closed in 1965. While in Russia and former Soviet countries is used gauge of 1,520 mm (4 ft 11 27⁄32 in), but for the models used the NEM. Therefore, the gauge is 32 mm, rather than about 34 mm. In this models of the rolling stock are made in scale 1:45. The smallest scale for O Scale is 1:58. In O scale terms, this is known as Mini-O Scale and in S Scale terms it is known as Major S Scale.
O-27 Scale A Lionel variant on O-scale. Has a slightly taller track and sharper curves than O scale. Often, but not always, mechanically compatible with O-gauge trains.