Description: YLI Woolly Nylon is a 100% nylon heat set serger thread of incredible strength, stretch and memory. It's soft enough to snuggle next to a baby's skin and full enough in its relaxed position to provide ideal coverage for seams and rolled edges. Excellent for both upper and lower loopers of your serger. Perfect for rolled hems and edges, ruffles, swimwear, aerobic wear, kids' clothing, knits and lingerie. 100% Nylon. 1094 yard. #139 Navy Blue.