The multi-model cabability of ENGINO TOY SYSTEM is proportional to the number of parts contained in the sets. The inventor pro series is the ultimate range more suitable for intermediaste and advanced users who literally "play to invent" ! The models created with these sets are bigger and more elaborate and can move with the new compact dual output motor. The series starts with the 40 models set and goes all the way to the 100 models set which has 2 motors and extra gears for even more complex builds. Each set contains printed instructions for selected 10 models while the rest can be downloaded free from engino's website.