The Simplicity Sidewinder is a battery opearted portable bobbin winding machine. The Sidewinder allows you to pre wind bobbins in preparation for your sewing project, whenever or wherever you want. Being very compact it can be taken anywhere you want to go and is incredibly east to use. Place the cotton reel on the spool holder, take the thread around the winding wheel and then wrap around the bobbin. Push the button to start and thats it! The machine automatically stops when the bobbin is full, or you can just press the button to stop it at any time. Please note, this product does not come with a power cord.