Back when I first started using an embroidery machine, I thought pre-wounds were great. I bought a box of NEB pre-wounds. Had 144 filled bobbins in it. That was back in maybe 2004. I still have a few bobbins left but now as my new machine uses larger bobbins, these pre-wound bobbins just rattle so I wind them onto the machine's bobbins. They don't fill it completely but there's a lot of thread on those pre-wounds. All my machine's have a bobbin winder on them and they all work fine so rather use them instead of buying pre-wounds that cost much more than me just winding my own. I ordered bobbin thread in various colors from BFC back when they were selling threads so I have quite a bit to last me a very long time.