The one I have is called a Needle Art Embroidery Guide. It slips on the straight stitch foot of old singers (or similar feet) and you use it to sew on braid or yarn to decorate items. The yarn slips through the loop on the end and over the groove closer to the foot (leaving some behind foot to start). Then the yarn is sewn down with the machine threaded normally. It is pretty cool, but I have never used mine. I did try it to make sure it slipped on the foot. Pat in NC