This little device is amazing. If you have used an electric winder, you know that they can go pretty fast and if you're not careful can cause yarn burn on your hands - if you keep holding the yarn in the same place. This device also tensions through the little spirals so you don't have to tension as you're winding. You just hold onto the handle and move it back and forth across the bobbin. It moves as smooth as if it was greased with butter. Very cool tool.