After the zipper is inserted, there's no visible stitching—you only see the zipper tab. The roller allows the foot to glide smoothly and accurately over your zipper or fabric. How it works: The "toe" section has rollers that glide next to the zipper teeth. A marking on the foot indicates the center of the foot. Position the needle in the middle of the foot opening. The foot is hinged to duplicate a normal pressing foot for smoother stitching over seams and bulky fabrics. The invisible zipper is sewn into a completely open seam. Stitch the seam below the zipper after the zipper is inserted. To use: Open the zipper and press the zipper from the wrong side to flatten the coils. Use a cool iron; the zipper coils are sensitive to heat and you do not want to melt them. The coils of the zipper fit in the ridge of the foot. After both sides of the zipper have been stitched, close the zipper. To finish stitching the seam below the zipper, slide the invisible zipper foot to the left so the needle aligns with the right side of the foot. Lower the foot and stitch the remainder of the seam. Secure the bottom of the zipper by stitching the tape to the seam allowance. Stitch through only the tape and seam allowance; no stitching shows on the outside of the garment. Four shank adaptors: Adaptor A is for most low shank machines including Bernina, Elna, Kenmore, Necchi, New Home, Penncrest, Pfaff, Singer, Universal, Viking and White. Adaptor B is for high shank machines including Kenmore, Singer Super High Shank, Necchi, New Home, Penncrest, Pfaff, Singer and Universal. Adaptor C is for most slant needle machines including Singer. Adaptor D is for all front mounting machines including New Home and White.