Just like our popular HO model, Atlas' new N Roundhouse is based upon a prototypical structure that was once used to house and service locomotives. Molded in appropriate colors, the basic 3-stall kit can be expanded by adding more units. For use with Atlas N Turntable and Motor Drive Unit (sold separately. Dimensions: 10 3/8 inches at its longest section x 11 inches at its widest section x 3 inches at its highest section. (Requires assembly. Glue not included)