This kit converts the standard one-piece hopping foot on the Crown Jewel (BLCJ18) or Tiara (BLTR16) into a two-piece system, allowing you to interchange quilting feet. It enables you to switch between a standard hopping foot and an open-toe hopping foot to suit your quilting needs. Additionally, this kit is required for using the creative couching feet (BLQ-CCF) with these models.