Small, powerful and even water-resistant, Sigma Sport's Mono FL lights the way and gets you seen. This mini-USB-rechargeable lithium-ion battery-powered taillight boasts a .5-watt LED that throws off more than 400 yards of visibility. It offers steady and flashing modes for 7 to 8 hours of run time per charge. It attaches to your seatpost, seatstays or helmet quickly and easily with its tool-free O-ring mount. It also sports a nice on/off switch that's easy to use even with gloves on. And you get a handy battery indicator so you always know how much power you have left.