Introduction to luminous shoelaces: This shoelace does not require a battery and only requires thermal energy to emit light, without harming the body or polluting the environment. This shoelace requires some light to make it glow at night before being used with a special craft. Before use, please place the shoelace in the sun or under a light, and use the LED light on your phone to illuminate it for 10 minutes The entire shoelace needs to be under the light, only illuminating a part, and only the illuminated part will glow. Specifications: Material: Polyester Colors: 6 Colors Dimensions: 39 47 inches