This rugged cast iron mitre clamps is just the job for heavy duty clamping metal sections for prep welding. The jaws are pivoted on the end of the copper coated screw that allows for a large degree of misalignment when clamping work pieces of different thickness. They can be used for mitre or T joints and with equal or odd material thicknesses. All the clamping surfaces, including the bases, are machined at 90°.