Unlike other monofilament threads 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 bobbin or top. Available in two colors, Smoke (for dark fabrics) and Clear (for light fabrics). MonoPoly is recommended over nylon monofilament threads because MonoPoly will not become brittle or discolour over time. MonoPoly is dryer and iron safe on medium heat.