Aerofil No. 120, Polyester Sewing & Quilting, 440 yd/400 m It's the thread designed to run without problems! For frustration-free sewing and quilting at an unbeatable price, you can count on Madeira Aerofil. High tensile strength and excellent sewing performance guarantee problem-free sewing. Aerofil stays knot-free and is very easy to thread..