https://www.rongduthread.com/products/heavy-duty-nylon-sewing-thread/ Extra Strong Nylon Thread Heavy duty Nylon sewing thread is composed of strong nylon 6 and nylon 6.6 continuous filament. Besides carrying remarkable tensile strength, the thread is supple and stretchy, which is necessary for sewing mattress, bedding, sofa, leather, sports goods, footwear, denim, jeans and so on.All Rights Reserved