N Scale Track Gauge - Code 55

Track gauge for code 55 rail at a gauge of 9mm.  This is the standard gauge for N scale (1:160 in the US, 1:148 in the UK, similar standards in other places but all using a 9mm track gauge).  It is also the appropriate gauge for HOn30, which models 30" narrow gauge in 1:87 scale, and for OO9, a UK standard for narrow gauge in 1:76 scale with a track gauge of 9mm.

Designed to work with code 55 rail that conforms to NMRA recommended practice RP-15, for example the code 55 rail produced by Micro Engineering.

The gauge has four prongs to hold the rails parallel for ease of laying track.  The prongs are placed more widely apart on one side to spread the gauge slightly on curves.  The widely-spaced prongs go on the outside of the curve.