From the manufacturer:
It glows! This may look like ordinary white yarn, but don't be fooled! When the lights go down, DIY Glow yarn turns up! This polyester yarn in a classic worsted weight is perfect for fiber artists of all skills and ages. Make glow-in-the-dark hats, scarves, and cowls for nighttime adventures, or add fun trims to costumes.
Weight Category: 4.
Content: 100% Polyester.
Putup: 1.75oz/50g/ 74yd/65m.
Gauge: 18sx24r = 4in/10cm on size US8/5mm knitting needles.
Suggested crochet hook size: I-9/5.5mm.
Dyelotted: we try but are not always able to match dyelots.
Care: machine wash, machine dry, do not bleach, do not iron, do not dry clean.
Imported.