Package Included: 2 pieces bike taillight , extra 5pcs batteries.Material :Products made of aluminium alloy material.(It 's not cheap plastic material)these bicycle lights are made of aluminium alloy and LED lamp beads, not easy to break, durable for you to use long time Also designed with silicone elastic buckle, easy for you to install and take down The elastic buckle is suitable for various kinds of bike, such as mountain bikes, road bikes, city bikes and so on.Fuction : Three Modes Of Switch: Full Light, Fast Flash And Slow Flash Mode, These Three Modes Help Or Alert Other Riders, Drivers, And Walkers Spot You When Riding In Low Light Or Complete Darkness.These ultrabright LED lights feature two lithium ion batteries and visibility up to a half mile. This helps other riders, drivers, and walkers spot you when riding in low light or complete darkness..Easy to install No need tools: these bicycle headlights can be installed and fastened in seconds without any tools or other equipment, and save you much time and effort Add a light to your bike, backpack, helmet or other areas, can help you to guide the way and keep you stay at night.