This iron Zoom meter can be both ways. It is used to draw in the seam value on the fabric around the pattern or seams to be ironed. At the slat there are all kinds of openings that correspond to all current joint values, namely, 1, 1.5, 2, 3, 4 and 6 cm. So you can put the size slat with the small notch of the necessary measures against the fabric and mark on the long side with a crayon. So you can without having to measure exactly right quickly add the right seam value. Seams or hems measure also during ironing.