Commodity name: LED fiber optic light-emitting hatHow to use: You can adjust the working mode of the product through the switch (long light - fast flash - slow flash - off)Lighting color: red light. yellow light. blue light. green light. orange light. white light. pink light.Using battery: Using CR2016 button battery, the long-bright lumi time is about 30 hours; the battery can be replaced by yourself.Commodity specifications: Adjustable cap circumference: 50cm-58cm (6 pieces of caps) manual measurement, the measurement method and tape measure are different, and the error is kept at about 2cmPackage included:1 x Hat