It is still packed from my move but I have the basic Sidewinder that I bought for a Brother who's bobbin winder didn't work. I looked it up to see what it says it fit and it sure doesn't have very good info... saw where it said it didn't work on Brother but that's not my experience -- maybe it is high end Brothers/embroidery machines?? I'll see if I can find it today and give more specific info.
It worked fine for my needs but I can say that I got much better results with the power cord and not using batteries. I've used with plastic bobbins for the Cheap Brother, and metal bobbins for my vintage badged machine. Not sure if I ever used it for the 301 or not.
This site has a pretty good list of machines that don't fit:
https://www.cutexsewingsupplies.com/...-bobbin-winder