The most popular scale/narrow-gauge combo is H0n3, which marries the 1:87 scale of H0 with slender, 10.5mm gauge tracks. The chief prototypes for the n3 tracks are the lines that meandered through mountain passes in the American West, especially in mining areas. Kadee, Roundhouse, and Athearn are just a few of the manufacturers who make locomotives, cars, and accessories in H0n3. Imported Japanese and Korean brass model trains in H0n3 are also collectible.
Another narrow-gauge format using the H0 scale is H0n30, whose 9mm tracks are even narrower than H0n3. While the 3 in H0n3 refers to the three-foot width of these tracks in full scale, the 30 in H0n30 refers to a 30-inch prototype. Thus, the two standards are very similar, one based on tracks that are 36 inches apart, and the other based on tracks that are six inches closer together.
Unlike H0n3, H0n30 is considered a builder’s scale because it requires tinkering with and retrofitting of N gauge tracks. Conversion kits are available, and some Japanese brass trains are sold in H0n30, but for the most part, this is a narrow gauge for collectors who like to get hands-on with their model trains.
More popular than H0n30 is On3, which combines a 1:48 O scale with large, 19.05mm tracks. Though twice as large than H0 scale, On3 has the advantage of lots of ready-to-roll cars, locomotives, and tracks. Kits are available, too.
Finally there’s Sn3, pairing 1:64 ratio S scale trains with 14.3mm gauge track. Like H0n30, there are not a lot of products out there for collectors, but that suits many Sn3 enthusiasts just fine.


1950's Marx Train Set
Marklin z- guage briefcase train set







