This metal daring foot with spring is for mending fabrics much like the low shank darning foot. You can also do free-motion embroidery with this foot. It moves up and down onto the material as the needle goes up and down into the fabric. It works in sync with the needle, when the needle is down into the fabric, the foot is pressing down on the fabric. When you use this foot, it is best to drop the feed dogs on the sewing machine, so it will allow you to sew in all directions. You will move the fabric around to create the stitching movements.
Embroidery / Darning Foot (metal)
Good service. Good product. Helpful on line advice to ensure I purchased a product to fit my machine.