Everyone always worries about how many lumens their headlamp is throwing out, but what about your rear? Making sure that cars can see you from behind is important, and the more warning you can give them, the better. The Niterider Solas tail light is a 2 watt tail light that will give drivers PLENTY of warning that you"re there. It"s one of the brightest tail lights we"ve ever seen. It also includes a "group ride mode" that lets you lower the flash brightness so you don"t blind your riding buddies when you take your pull out front. Quick release seatpost and seatstay mounts included USB rechargeable Long lasting lithium polymer battery Powerful 2 watt LED bulb with custom reflectors 4 modes (two flash, two steady) Up to 36 hours of run time on low steady, 4.30 hours on high steady