Bicycle Taillights Warning Lamp Bike Tail Light Self-Powered Magnetic Induction Cycling Accessories Features: brand new and high quality. - This taillight is based on the principle of electromagnetic induction, so it needs no charge and no battery. - The taillight lights up automatically during riding. The faster the speed, the brighter the taillight will be. - The whole taillight is very light and portable, so it doesn'for t add for extra weight to you. - Sealed with high-quality materials, waterproof in daily life. - It can be installed horizontally or vertically in various ways. Specifications: Name: Self-coming electromagnetic tail lamp Charging: Magnetically generated electricity Specifications: 53mm* 19mm*32mm Installation position: bicycle for seat tube Applicable models: round spoke wheel and flat spoke wheel Lamp bead: highlight LED lamp *2 Material: high quality engineering plastics Waterproof: waterproof for life Note: Transition: 1cm=10mm=0.39inch Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Package Includes: 1 Taillight 1 Generator 1 Instruction 1 Tie 2 Rubber Strap 1 Magnet 1 Generator Base 1 Taillight Base 2 Rubber Pad