This thread winder is designed to be used with card bobbins and stranded embroidery cottons. There is a little peg that corresponds to the hole in the cardboard bobbins, which will then hold to bobbin while you wind the thread onto it.

However - these also make a terrific, inexpensive cord twister. Carefully screw a cuphook into the plastic after removing the peg (shown in the second image) and you now have a way to twist a length of cord. Do not remove the cuphook - to do so will probably break the plastic, instead have one for bobbins and one for twisting. If you prefer not to use the cuphook, threads can be tied through the peg hole.