ADVANCED DESIGN: USB rechargeable front and back lights, built in 2000mAh rechargeable lithium battery for Headlight and built in 330mAh rechargeable lithium battery for Taillight. 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, slow flashing and fast flashing. EASY INSTALLATION: The Headlight is equipped with a mounting bracket that can be easily fixed to the handlebar. The silicone mount strap for Headlight and Taillight are designed with four openings that tightly fit around most size seat posts. Both Headlight and Taillight can be easily loosen and fasten, and no tools are required. 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.