a device for calibrating an extruder plastic profile having a calibration unit for the profiled strand coming - out of a molding profile nozzle is described , the calibration unit having a molding body enclosing the profiled strand , having calibration surfaces , which press against the profiled strand , and vacuum slots , which run in the calibration surfaces transversely to the passage direction of the profiled strand and are connectable to a partial vacuum source . in order to provide advantageous construction conditions , it is suggested that at least individual vacuum slots penetrate the molding body transversely to the passage direction and be closed on outside of the molding body using a removable cover .