This is a blind hem foot, sometimes also know as a blind stitch foot. As the names suggests, it’s main function is to help you sew a blind hem which is an awesome technique, but not something I use very regularly. However, it can also help with something I do almost every day - topstitching! The foot has a little adjustable ledge which you can move from side to side. If you position that ledge in your seam, it will then stay in there as you sew, enabling you to sew your topstitching perfectly st