Bicycle back light USB battery

- LED light
- Mode: 4 modes. (constant,slow flash,explosion lash and flash in order)
- Brightness: 15 lumens
- Product Dimension:7.5* 3* 2cm
- Mounting Placement: bicycle seat post
- Suitable Tube Diameter:12-34mm
- High quality internal lithium battery,only need about 2 hours to be fully charged while be used for about 12 hours.
- USB rechargeable bicycle taillight and auto cut off when fully charged.
- Super waterproof,make you riding freely regardless of rain.