On30 Scale
On30 Narrow gauge O-scale models running on HO gauge track. This scale was initially created by American "kit-bashing" modelers desiring large scale narrow gauge at low cost, at a time when the existing On3 market was dominated by expensive brass models. They put small O-scale superstructures on HO-scale mechanisms and trucks, but when the large company Bachmann issued train sets — originally intended to run around Christmas trees — On30 really took off.