These were originally made of wood many years ago and called "building boys", later the official name became "Billy-Ding Boys" some 60 years ago. They vanished for a while but are back. These are great for building, balancing and teaching little hands how to build. They teach creativity and when the child moves into grade school they are still fun for a while...then forgotten...until they are brought out for visiting children to delight in. You also see high school students working with them in physics! As a physics teacher I brought them to class where they were used to make great problems for students. I recommend them for ages 2-7 and then again for school projects and physics teachers. We still have some that are going on 80 years old. Mike C.