Building Blocks Developmental Preschool What Are These Hinged Building Blocks Called?

What are these hinged building blocks called? - building blocks developmental preschool

My son berserk in the nursery by a kind antique bathtub Lego bricks, which were a sort of hinge on one end and then turn in May, I asked what they were and how I could find, but they said they would probably be sold only on TV , and I can not remember the name. Blocks "something"? It is a Lego product. Doing this kind of building blocks known to everyone?