replacable screw is a new developed product, the screw can be diveided into many pieces and can seperate very easy Replacable ScrewScrew Diameter: 12mm-200mmMaterial: EN41B, SKD61Grade: Nitrided, bimetallic and full-hardened for choiceAppliance: Plastic injeciton and extrusion machinesAdvantage: economic and efficencyDepth of Bimetallic Layer: >2mm