YLI has many option for bobbin threads. They have their Wonder Invisibile which is a nylon Monofilament. Some people think nylon is not as good as polyester so they have added the Poly Mono Thread. Both are excellent products. They also have the Lingerie and Bobbin thread which is an excellent bobbin thread for most applications. We have the Wash-a Way thread that does wash out after you have completed your work. Prewound bobbins in Polyester and prewound bobbins that are YLI Soft touch Thread.