We review all HO scale products presented by the most prestigious brands taken around the world, about american model railroading. Each features will be evaluated on the basis of rigorous parameters (manufacture, assembly and quantity of details, realism and fidelity with the original prototypes, functionality, packaging and much more). Before each review, PRRHO searches for images, news and informations about the original prototype. The tested models are taken from the author's collection created for the project Conrail Early Years in HO scale. The complete AT Collection is available from the main menu.