This foot helps regulate the thread tension allowing the stitch to lie flatter. Use with medium weight fabrics. This foot is equipped with a pin which acts in a similar manner as the stitch finger on a serger. When the pin is placed along the edge of the fabric, it reinforces the edge as the stitch forms, preventing tunneling of the fabric. The right side of the sole is cut away so the stitched edge of the fabric can move smoothly under the foot without any unnecessary pulling or stretching. Another application for this foot is sewing a narrow satin stitch. The satin stitch can be formed over the pin for a raised satin effect such as in charted needle work. Using the pin in the foot rather than knitting needles simplifies the process, especially for beginners.