MonoPoly is a polyester monofilament thread. Commonly called an 'invisible thread' due to its fineness. Invisible thread is often used for invisible appliqué when the stitching is not meant to be seen. • Available in 2 colors, clear and smoke. • Use MonoPoly for invisible appliqué, quilting, bobbins, and apparel. • Reduced-sheen invisible thread. • .004" (.1mm) in diameter (90 denier) = Very fine thread. • Iron and dryer safe (medium heat). • Will not become brittle over time (nylon monofilament thread tends to go brittle). • Will not discolor (nylon monofilament thread tends to "yellow" over time). • Strong with low stretch • Soft & pliable