The thread can be used in any kind of sewing machine. The prewound bobbins come in size L and size M. My Voyager 17 is a stretched industrial Singer and it takes size L bobbins. I love the magnetic prewound bobbins, but they are not available in all colors. I have used the thread to wind my own bobbins too.
What Singer sewing machine do you have? Different models were made with different size bobbins. Here is one list I found:
http://www.inthehoopdesigns.com/x-ca...BobbinSize.pdf
You can also look up your machine here:
http://www.sewingpartsonline.com/?gc...FchDMgodtEQA7Q
They offer the correct bobbin for each machine, so you may be able to figure out the size from that.