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. 52% Cotton, 45% 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 men's shoe size 7-13 and women's shoe size 8.5-14.5.