Serfas 5 Led Usb Rechargable Taillight (Black, One) The industry's most technologically advanced safety lights All lights are robs compliant and all testing is done in house More efficient leds & high quality lenses to increase brightness & Clarity USB Rechargable 5 LED Taillight Smart USB Charger makes it impossible to overcharge Quick and Easy installation - No tools required Can be mounted practically anywhere 4 modes that includes 2 flash modes