I use one with my longarm. If I run out of thread in the middle of a quilting design, I don't want to muck with moving the design and re-setting up. The machine is hard to thread, so I am able to avoid that as often as I can. Also, I HATE that the sewing machine's needle goes up and down as though I'm sewing when the bobbin's winding. Somehow it just seems it will wear the needle out that much faster....don't know if that's a fact, but I use the Sidewinder just the same.

I picked one up for my 'Stretch' machine (mid arm on frame). I probably won't use it for my Pfaff or Brother, but the 'Stretch' has the bobbin winder in an awkward spot for me to wind bobbins on. Also, I don't want to have to re-tread my 'toy'. I also can sit and watch TV while winding bobbins.....