They can be good but know that not all machines can use those bobbins. I have a Viking and because it winds the thread differently I can't use mine for it, I can use it for my Kenmore though. It really doesn't take that long to wind bobbins on my machine so I rarely use it for that. I got it to wind bobbins with different colors of thread for my applique so that I'm not taking the whole spool with me when I'm on the go.