For Era III, the following three types of cars are of interest: K2, K3, and K4. K2 and K3 were built for many years (K2 since 1900, K3 since 1913), and they are available in various versions with different wheelbases while maintaining the same main dimensions. The SBB kept the partially outdated series in service for a long time, so the K2 was still in operation until the 1980s. The Hobbytrain model is completely newly designed from the ground up and is structured like a construction kit, allowing for various buffer, door variants, and wheelsets to choose from, which enables a multitude of variations across the eras.