This motion-activated blinking light never needs batteries...ever! Utilizing motion-activated, kinetic energy, Wink N Blink's bright, blinking light will not diminish and weaken over time like some battery-operated designs. With no battery disposal, it offers an environmentally-friendly design you can feel good about for years of reliable service. Perfect for use on horses, dogs, riders, athletes, backpacks and more, this convenient blinking light increases nighttime visibility. Its convenient, clip-on design gives you versatility for a variety of applications. This eco-friendly, ingenious light is waterproof for reliable performance in rain and snow as well as during swimming. 100% satisfaction guaranteed. Green.