The double rotors of the DR line are flexible and efficient machines, designed for special material processing. The same reliability and strength of the double shaft shredders are combined with the control of the size of the output material, typical of the single-rotor, allowing heavy use. The use of interchangeable shafts and the application of selection grids allow to obtain a constant and controlled size. Furthermore, in a limited space the machine produces double, since the two opposite rotors generate a double screening surface compared to a traditional machine of this length. The technology applied can be developed with an electric motor or with a hydraulic unit for particularly heavy use.