Seam tape is used to strengthen the seam of thin and stretchy fabrics. You use it before you sew the two parts together, because it makes the seam easier to work with. For lapels, collars, score lines and diagonally cut decorative lines, in the seams of stretch fabrics (jersey, cotton) and on the pockets and fold lines of hems and vents. Also useful for better feeding under the sewing machine of leather, suede and imitations thereof, and with wafer-thin fabrics. The seam tape is flexible and thin, and can be easily pressed flat