Add an environmentally-friendly taillight to your bike with this product is a good choice. Built-in rechargeable battery powered by solar. It has two bulbs, there are 3 luminous mode(quick flash, flash and constant light). 2 hours of charge in the sunshine will give you 4 hours of constant light and 8 hours in flash mode. There is a switch for you to change the mode and turn off the light. Comes with adjustable clamp to fix the light on your bike Made of solid and durable plastic.