These socks glow in the dark! Hold them up to light or walk outside in the sun before turning off the lights to watch the special thread glow. 56% Cotton, 41% Polyester, 3% Spandex. Our threads are certified by OEKO-TEX® Standard 100, which means we leave out harmful chemicals to keep your skin safe and happy. Approximately fits women's shoe size 5-10 and men's shoe size 3.5-8.5.