Build N Roll comes with 44 natural & colored blocks, and 3 wooden balls. The set also includes a special accessory, which can be used to construct a windmill. It is compatible with the Plan Toys Construction Set. This set provides opportunity for children to be their own designers. They can construct tracks of various kinds..through designing, planning and changing the track to form a loop; using their imagination while developing intellectual and thinking capacity. The special tracks create excitement because they can be adjusted various ways; straights, curves, slopes, all kinds of designs can be created. Desiging is fun, but watching the balls go around the track creates additional fun!