Tools are cylindrical in shape. Sometimes they are called round dies and sometimes roller dies. Cylindrical die form rolling machines use two, sometimes three, dies of the same shape and size. The dies rotate at the same speed and in the same direction, and they shape the part as the distance between them is narrowed.
There outstanding characteristic is that the distance between the dies can be set freely according to your own requirements, and because of the rotation factor, it's like having an infinitely extendable work surface. They are the most responsive to perfect shaping. Because of that, cylindrical dies are used for a huge variety of parts going far beyond the capability of simple threading platforms. The down side is that, because of that very factor, they are less production efficient than the other two kinds of form rolling machines.