These are 2D photo flats glued to foam core board they are ¼ inch thick and can be layered to create the illusion of depth. Each building is a photo of a real building in the real world giving real life weathering and detail. Each building has been re-sized to scale and photoshoped to remove as much modern items as possible so they can be used on almost any era layout. The best effect can be achieved by layering a smaller scale building behind a larger one ( N scale behind HO) with a small spacer between them this gives a forced perspective and when viewed from an angle you can see behind the front building. You can alternate each row of buildings with building fronts and building backs. The first row by the tracks being building backs, the next row building fronts so it looks like you are seeing the fronts of buildings on the next block. Trackside flats look best when placed behind a row of 3D models
HO is the most popular scale of model railway in the world.
According to the NMRA standard S-1.2 predominantly used in North America, in HO scale, 3.5 mm (0.1378 in) represents 1 real foot (304.8 mm); this ratio works out to about 1:87.1. According to the MOROP standard NEM 010 predominantly used in Europe, the scale is exactly 1:87. In HO, rails are usually spaced 16.5 mm (0.64961 in) apart which models the standard railroad gauge of 1,435 mm (4 ft 8 1⁄2 in).
N scale is a popular model railway scale/track gauge.
Depending upon the manufacturer (or country), the scale ranges from 1:148 to 1:160. In all cases, the gauge (the distance between the rails) is 9 mm (0.354 in). The term N gauge refers to the track dimensions, but in the UK in particular N gauge refers to a 1:148 scale with 9 mm (0.354 in) track gauge modelling. The terms N scale and N gauge are often used interchangeably. An advantage of N scale is that it allows hobbyists to build layouts that take up less space than HO scale, or put longer track runs into the same amount of space, because the models are smaller (by nearly a half) than they are in HO scale (1:87). While N scale is quite small, it is not the smallest commercially available scale, as Z scale is smaller yet at 1:220 and T scale is 1:450 or 1:480.
O scale (or O gauge) is a scale commonly used for toy trains and model railroading.
Originally introduced by German toy manufacturer Märklin around 1900, by the 1930s three-rail alternating current O gauge was the most common model railroad scale in the United States and remained so until the early 1960s. In Europe, its popularity declined before World War II due to the introduction of smaller scales.
O gauge had its heyday when model railroads were considered toys, with more emphasis placed on cost, durability, and the ability to be easily handled and operated by pre-adult hands. Detail and realism were secondary concerns, at best. It remains a popular choice for hobbyists who enjoy running trains more than they enjoy other aspects of modelling, and collecting vintage O gauge trains is also popular - there is a market for reproduction and vintage style models also. A number of changes in recent years have addressed the concerns of scale model railroaders, making O scale more popular.