Excellent for both the upper and lower loopers of your serger and can be used in the bobbin of your sewing machine. Woolly Nylon is great for rolled hems and edges, ruffles, athletic wear, swimwear, aerobic wear, kids clothes, knits and lingerie. Woolly Nylon is full enough in it's relaxed position to provide ideal coverage and gives you the elasticity you can not achieve with other threads. YLI Woolly Nylon is a Textured 100% nylon, heat set thread of incredible strength, stretch and memory. 1094 yards per spool.