I have a good friend who always uses it for her practice designs, for both bobbin and top. (She has a Viking, but I can't remember which one). I have a Janome 11000 and it does NOT like embroidering with serger thread. So, as others have said, it's worth testing on your machine (if its not a Janome 11000). I looked inside some of my cones and there is a 70 printed on the sticker, so maybe that's the weight. It doesn't specify what the 70 is.