OO gauge

Common card · No. 342764

OO gauge or OO scale (also, 00 gauge and 00 scale) is the most popular standard gauge model railway standard in the United Kingdom, outside of which it is virtually unknown. OO gauge is one of several 4 mm-scale standards (4 mm to 1 ft (304.8 mm), or 1:76.2), and the only one to be marketed by major manufacturers. The OO track gauge of 16.5 mm (0.65 in) – the same as the 1:87 HO scale – corresponds to prototypical gauge of 4 ft 1+1⁄2 in, rather than 4 ft 8+1⁄2 in standard gauge. However, since the 1960s, other gauges in the same scale have arisen – 18.2 mm (EM) and 18.83 mm (Scalefour) — to reflect the desire of some modellers for greater scale accuracy.

Read on Wikipedia · Image Photo by William J. Grimes, Original uploader was William Grimes at en.wikipedia, Public domain