Size: 125mm 150mm 175mm 200mm 250mm 300mm 400mm 500mm. Material: Made from high grade tool steel stress relief against distortion, precision ground and hardened. Application: Easy to use in precision clamping of parts indrilling boring, milling, prinding, assembly work, etc. Easy Storage: Set comes packed in a wooden case for easy storage, protection and transportation. Package: 8 pcs parallel blocks.