These reduced-sheen monofilament polyester threads are the best choice for invisible thread. Unlike most monofilament threads, which are made from nylon, MonoPoly is 100% polyester. Commonly referred to as an 'invisible thread' due to its fineness and reduced sheen, MonoPoly is great for the either the bobbin or the top. Available in two colors, Smoke (for dark fabrics) and Clear (for light fabrics). MonoPoly is ideal for invisible appliqué and quilting when the stitching is not meant to be seen. MonoPoly is recommended over nylon monofilament threads, because unlike nylon thread, MonoPoly will not become brittle over time and will not discolor or yellow. It is dryer and iron safe on medium heat.