This is a minimal add-on kit that assumes the purchaser already has an 18" radius track on which to add. The diagrams on the box are misleading if one assumes that one can build any of the track layouts without any previous 18" radius track layout. Generally, I really like Bachmann products. The nickel-silver E-Z track concept is unequalled. The ad should clearly indicate that this is an add-on if the prospective buyer already has a compatible 18" radius set up. I understand what "expander" implies. It is not readily apparent, however, that one needs to have already purchased a few hundred dollars in 18* radius track.