I will confess that I hate the bobbin running out in the middle of something. I also hate having to unthread my machine to wind another bobbin so I purchased the Easy Winder. I love it. I don't mind sewing and really put the peddle to the metal. Even with my stand alone embroidery machine I like to use variegated thread whenever possible because I don't have to keep changing thread. I can purchase prewound bobbins for my Bernina in white or assorted colors. I will confess I use the prewound white ones for most of my projects that let me use white thread. Just another time saving device. I have wound a lot of bobbins on my Easy Winder and still haven't had to change batteries.