I wind my own usually, I use OESD bobbin thread. It comes on a 6000 yd cone and lasts fairly long. I have a cone of white and one of black. If I am doing free standing lace or something that will show both sides, I use the same thread in the bobbin as I do in the top. I tried the prewounds but actually like winding my own better but it has been a while since I have tried any of the newer prewounds and actually I haven't done as much embroidery the last several years. I have heard that bottom line also can be used as a bobbin thread and I do have several colors of that so now that I got two new machines that can do embroidery, I just may give it a try