This insole contains tourmaline and it can heated spontaneous ,and its main effect is to message the feet and keep warm it may not reach to a high temperature, because it makes people feel uncomfortable Benefits keep warm and keep healthy long-term effect and durable wear comfortable and beautiful, does not affect work study and life; without using any energy, reliable, and eco-friendly that is markedly heat-based products, no external power and heat. Material: Cotton,Tourmaline powder balls,Far infrared rays balls Color: as shown Size: 27cm Package Include:1 Pair Shoes  Insole Note The color is just for reference only. It may slightly different from real item. Please allow the size for 1-3cm difference due to manual messurement. Thank you!