3mm

3mm scale is a model railway scale of 3mm:1ft used for British prototypes. Introduced as British TT gauge, It sits approximately halfway between British N gauge and OO gauge, but is not as popular as either and there is no longer any mass manufacturer ready-to-run support. As with other scales, the original models had to be scaled up to fit motors so British TT gauge is 'narrow', which lead to the development of 14.2 mm (0.559 in) gauge 3mm finescale. Other gauges are also used to model other prototypes (Irish broad gauge, Brunel broad gauge, 7 ft 0+1⁄4 in/2,140 mm). For narrow gauges, N gauge 9 mm track represents 3 ft (914 mm) gauge; Z gauge 6.5 mm (0.256 in) track represents to 2 ft 2 in (660 mm) gauge