Madeira's Serene Sky 1528 100% polyester machine embroidery thread, Polyneon, is constructed of a specifically developed raw material, eliminating looping, puckering and virtually all thread breaks. Suitable for almost any application, Polyneon's unique formula makes this thread extremely durable and smooth running for high-speed embroidery machines. Vibrant colors are glossy, as well as resistant to chlorine bleach. Choose Madeira for the highest quality embroidery thread available.