Meet the ultimate N scale retaining wall system. This simple, infinitely expandable system allows you to build retaining walls any length you want. The modules are engineered to have a seamless connection that won't take away from your beautiful model railroad. On the back of each module, there is a housing for a standard 6x3mm magnet. There are also different types of modules such as tunnel portals, full size modules with and without connectors, and finally half size modules, with and without connectors. This is labeled in the print plate screen. Happy printing!