This 1420 yard spool is a 60wt polyester thread. Designed with award-winning quilter Libby Lehman, The Bottom Line makes a fantastic bobbin thread for any type of sewing. Its lightweight, blendable colors are so easily matched with any top thread. (Yes, you can use Bottom Line as a top thread, too!) Invisible appliqué and binding is a breeze with Bottom Line as it glides through layers of fabric without any extra friction. It's also fantastic for micro stippling due to the fine nature of thread. Lint Free. We recommend a Topstitch #70/10 Sewing Machine Needle. Set your tension to 4.0.