This foot has two versions, one for BERNINA models with a maximum stitch width of 5.5mm and a coded version that works with models that stitch up to 9mm wide. One side of the foot #12/12C is higher than the other and when making piping, the raised portion of the sole accommodates the multiple layers of fabric in the piping seam allowance, while the groove allows the filler cord to pass easily under the foot, and the lower section of the foot keeps the fabric in contact with the feed dog of the machine. The extra space under the foot also helps prevent knit fabrics from being stretched as they are stitched. The engraved line on the top of the foot indicates the right edge of the groove. Along with sewing heavy knits and making piping, Foot #12/12C is also great for couchiong cording and attaching strands of beads.