Robinson Anton makes a number of different types of threads and sizes. I have RA polyester, rayon, and cotton threads. I use the RA polyester thread when I am embroidery free standing lace for things like bookmarks. It is a fairly strong sturdy thread. I used a lot of the rayon for embroidery as it has a nice luster and looks beautiful...but it is not strong enough for use in piecing. I use 50 weight cotton RA for embroidery of fine free standing lace like delicate snowflakes and have also used to applique as it is fine and blends in. I am sure these threads can be used for other purposes too. I would go to the manufactorers website and do some researches on various threads as they make several kinds for different uses. I have some coats ad clarks dual duty thread and find it fine to use for piecing although a bit thick and what I mostly use it for is top stitching on binding which I apply by machine when I want the color I have. I would not use dual duty for embroidery or even long arm quilting as it, if I remember correctly is a poly thread in the core which has cotton thread cross wound around it and tends to fray in break in embroidery machine or at the speeds long arms go.