Just want to mention that there's a big difference between 50wt 2-ply and 50wt 3-ply. 50wt 3-ply is the commonly used regular sewing thread. 50wt 2-ply is much finer. One reason I like Aurifil is that it is such a smooth thread -- very little lint and, because it is fine, the bobbin holds much more of it.