Set comes from a smoke free, pet free, climate-controlled environment and is compatible with MTH, Atlas, Weaver, Williams, and K-Line train systems. The AA units were only out of the box for the photos and less than 1 minute test run. The observation car is the only one out of the box for a photo. Also, this set is very heavy and I will be paying some of the shipping. Have to move and pay more med bills so some of the trains have to go. Thanks for L@@KING!