Durable Rot Proof UV Resistant Gutermann Upholstery thread is extremely high strength. It can be used indoor or outdoors on , vinyl fabrics, nylon, canvas and duck, denim, and upholstery fabric. Fix up your boat, camper, sofa, or swing. Soft and flexible ensuring neat, flat seams. No strength loss due to washing or dry cleaning. 100% polyester. 300 meters/ 328 yards. How many spools to order? General rule - 1 spool for up to 5 yards of fabric, 2 spools for 5 to 10 yards, 3 spools for 10 to 15 yards etc.