Nite rider solas 3w usb 40 lumens rear lightthe solas 40 has a powerful led 4 modes 2 flash2 steady and is usb rechargeable theyve implemented what they call group ride mode for cyclists who still want to stay visible and safer but not annoy others in the pack featureslumen output 40 light levels 2 steady 2 flash run time 430 3600hrs charge time 400hrs weight 54g battery li po 100mah x 1 seatpost mount usb cablebuy nite rider accessories from chain reaction cycles the worl