1.ADVANCED DESIGN: rechargeable bike light, built in 650mAh rechargeable lithium battery for each light. 2.FOUR LIGHT MODE OPTIONS: The Headlight and Taillight feature an one-touch switch with four different lighting modes depending on your preference. Include full brightness, half brightness, fast flashing and slow flashing. 3.EASY INSTALLATION: The silicone mount straps are designed with two openings that tightly fit around many size seat posts, handlebars, seat risers, backpacks, helmets and stretch to keep lights secure and firm. They can be easily loosen and fasten, and no tools are required. 4.MUTIFUNCTION: This bike light set is versatile enough for cycling, hiking, camping, or any outdoor activity and can be used as emergency flashlight. This is great for cycling at night or in places where visibility and safety are concern. So, just start your next adventure with us.