MonoPoly Invisible Polyester Thread .004mm 2200yds This reduced-sheen monofilament polyester is the best choice when it comes to invisible threads. 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 colours, Smoke (for dark fabrics) and Clear (for light fabrics). Monofilament Polyester. For Quilting and Thread Painting.Heat resistant.