The Double Eye Needle has two eyes, one above the other.
This allows you to run two regular sewing threads through the eyes, which will give you a heavy top stitch look. By varying the thread colors, decorative stitching may be accomplished with added interest.
This is much easier to use than a top stitch needle with a heavy thread in most machines.
It works very well with the Girlfriends Shirt by L.J. Designs.