Serfas Thunderbolt Rear Light

At 35 lumens, this light is bright enough to be seen clearly in urban environments and during dusk or dawn. While it isn't the most powerful option on the market, the 30-LED strip design creates a wide flood of light that is highly effective for increasing your visibility to drivers from multiple angles.

Yes, the removable straps are designed to be flexible and adaptable. They can stretch to fit most standard round seatposts as well as many aerodynamic or non-traditional frame shapes.

The unit features an integrated charge indicator light that alerts you when the battery level is low. This helps you avoid the frustration of the light dying mid-ride.

While the light is designed for cycling in various conditions, it is not fully waterproof. It is water-resistant enough to handle light rain or road spray, but you should avoid submerging it or using it in heavy downpours.

You have two steady modes (High and Low) for consistent visibility and two flashing modes (High and Low) to help draw extra attention to your position on the road. Flashing modes are generally recommended for daytime use to extend battery life and increase visibility.