The new sewing unit 1931-5 allows topstitching of trousers flies optionally with one seam or with two seams. Thes flexible applications and the first-class sewing results based on the approved class 1911-5 increase the efficiency and flexiblity of use. As tried and tested, the waistband edge of the workpiece is positioned at the laser marking. The seam end is precisely in the seam shadow below the waistband. With the new sewing unit 1931-5 it is possible now to sew a parallel second seam with a distance between 2.4 mm and 6.4 mm to the first seam. The distance is determined by exchangeable contour rollers of 1/10 mm according to the costumer's requirements.