60 wt colored bobbin thread on the spools. 60wt thread can be used as bobbin thread, as well as top thread. As Bobbin Thread Since A size bobbins are not available in colors, you can wind the thread on the bobbins manually. It can be used with all types of threads including metalics, so you are not limited to using specific thread. It also provides greater bobbin-fill capacity. We always recommend using 60 wt thread as a bobbin thread for embroidery. When used as bobbin thread, your embroidery looks much richer and the thread is secured without grabbing the fabric… This results in beautiful curves and sharp points. As Top Thread As top thread, it can be used for small lettering with a delicate look and lace designs for a soft and gentle finish. Plus it can be used for regular embroidery designs if you would like your embroidery look smaller and have a miniature look. Overall, your project will be free from stiffness and full of life!