The brass plate protects the workpiece from damage. The combination of nut DIN 6330 B (EH 23070.)/conical seat DIN 6319 G (EH 23050.) on the clamping bolt and thrust pad DIN 6311 (EH 22560. removable) on the adjusting screw compensates for the lack of parallelity. The clamp can be used either way (soft or hard clamping surface).