It's not my most favorite foot, but for certain jobs it's indispensible. It's for stitching cording, and has a tunnel about 3/8 inch wide just left of the needle. The tunnel guides the cording so you can stitch very close and very consistently. IMOH, it works better for the job than the adjustable zipper foot, which I also love. I used it for making some hangings for my church,and the results are terrific.