Product name: Bike Light Product size: 2.8*0.8in Battery:300mAh Endurance:3-4h Product material: ABS Product features: 1. High-brightness, waterproof, shock-absorbing bicycle tail light. 2. USB rechargeable for convenience, with a rotatable design. 3. Features alternating slow flash, quick flash, alternating quick flash, and constant light modes. 4. Provides enhanced safety for cyclists in various lighting conditions. 5. Versatile and user-friendly design for easy installation and operation on bicycles. Precautions: 1. As we all know , the different computers display colors differently, the color of the actual item may vary slightly from the following images. 2. If you feel difficult to choose the size, you can feel free to contact me we will give you some suggestion, but it is for you reference only. Package includes: 1 pc Bike Light