Elna One Step Buttonhole Foot 7mm J (Cat C). Thin fabrics call for finer threads & needles, but what if you are making a buttonhole in a delicate blouse? Add cording to give strength without bulk. Hook fine filler cord around the spur on the back of the buttonholer & up through the forks before sewing the buttonhole. The Elna One Step Buttonhole Foot 7mm J can be used to create perfectly aligned buttonholes with a ONE-step buttonhole machine. Sliding plate under foot has conveniently spaced markings to start & stop your buttonhole at precisely the correct point. For Elna Top Loaders Category C. Please note: This item cannot be cancelled, refunded or exchanged.