IDT guarantees that the feed dogs are perfectly synchronized! Only Pfaff has IDT built into its sewing machines.
During sewing, the fabric is fed simultaneously from both the top and bottom. Absolutely nothing can slip when working with fine fabrics or several layers.
It's wonderful for quilting because piecing and quilt blocks match exactly. Even long lengths of heavy fabric (typical for home decorating projects) can easily be sewn from beginning to end.