Tiny but tenacious the Stix Sport tail light packs a 18-lumen punch that can be seen from multiple directions. Its wide-angle light & six modes—ranging from steady to flash—make you highly visible to drivers which will increase both your safety & peace of mind while riding. The tail light runs for up to 18 hours depending on mode choice & is charged easily & conveniently via USB (Universal Serial Bus).> 7 to 18 Lumens output.> 2.5 hours to 23 hours runtime.> Charge in the USB (Universal Serial Bus) port of any laptop or phone charger in two hours (no extra cables needed)> Flexible mounting system works with handlebar & seatposts from 22.2mm up to 35mm in diameter as well as most seatstays. (Aero strap mount available separately)> Six modes including: Steady High 16 Lumens Steady Low 7 Lumens Power Surge 16 Lumens Power Flash 18 Lumens Disco Flash 7 Lumens Eco Flash 7 Lumens> Red/ Green battery charge level indicator.> Additional mounting options available separately.