Vanadium steel 31CrV3, chrome-plated, carefully forged and expertly machined, washer curved and at an angle of 10°, with UD profile for careful transmission of force, overloading is indicated by deformation, deep-set or countersunk nuts or screws can be safely operated even with the curved washer, high-quality industrial quality for continuous use under heavy-duty conditions, jaws ground to exact nominal size for optimum contact surfaces