Quadrilla sets by Hape have been an Oompa favorite for many years... and our customers continue to come back for more! These sets are wonderful not only for their high entertainment value, but for all the skills developed through building one of these challenging marble runs. Little engineers will hone dexterity skills, problem solving skills, and spatial reasoning. Please keep in mind that these sets are recommended for children four years and older; however, young children will typically need assistance from an adult or older sibling to successfully complete a track. This is a wonderful family activity that even adults will thoroughly enjoy!