I'm sorry that the title is very obscure, but I'm not sure how else to say it. I've seen some products do this before where you can spin a part(that most like has some kind of cord) and the cords inside aren't twisted or broken.

I wanna know how they do this. I was thinking something like where the cord hooks up there is a piece with an inlay that it revolves on. Therefor not twisting the cords.

If anyone understands what I'm saying or could enlighten me, please comment.