• Material: Tourmaline, Polyester Cotton. • Color: Black, Blue. • Size: One size. • The package includes: 2 pairs of self-heating socks. • They quickly retain heat when rubbed with the feet. • Promote blood circulation and relieve fatigue. • Suitable for outdoor activities such as climbing, skiing, fishing, jogging, hunting, cycling, and hiking. • The bottom of the socks has a tourmaline design that self-heats.