I have one and the main reason I bought it was so that I didn't have to unthread my machine while working on a project to wind a new bobbin. I wind 5 or 6 bobbins before and start a project but often that is not enough. Also, I seem to have to have every new gadget that comes out. Widh I had waited to get mine because now they have improved it and they have one that holds those huge spools of thread like the ones used for sergers.