YLI Wooly Nylon is a Textured 100% nylon, heat set 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. Wooly Nylon gives you elasticity and ravel- free finishing that's impossible with other threads. 1094 yards per spool, 6 spools per box. Sold by the box.