Good for you and the environment! Fibers leftover from making other yarns -- the soft too-light fluff, the bits that otherwise would have been lost to the waste stream -- are used to make this handy, durable, and surprisingly soft high quality yarn. It's called "clean cotton" because it's a yarn you can feel good about using.
85% recycled cotton / 15% recycled polyester
Machine wash, tumble dry low
#4 Worsted weight
131 yards / 75g
Needles: US8 knitting; US I/9 crochet
Gauge: 18sts/24 rows = 4" in stockinette stitch
24 single crochet / 16 rows = 4"