Sometimes you just don't know how late you'll be out on your bike. You can wear all the reflective clothing you like, but once you're out past sunset, you're definitely going to want to have some lights on your bike. The Azonic Sulu CR Rear Light can stay unobtrusively attacked to your seatpost so that you can simply forget about it until that unplanned after dark ride, when you'll be mighty grateful you can reach down and switch it on. Since the light weighs only 25 grams, you won't have to worry about added unwanted heft, especially if you have taken a great deal of care to shaves grams here and there off your rig. The rear light has a 7 lumen strength, which isn't going to make anyone go blind looking straight at it, but will certainly be enough to alert drivers and even other cyclists to your presence on the road. You can set it to one of three settings, constant, long flashing, and rapid flash, depending on what sort of traffic you are facing. And keep in mind, the mode will impact the run time: on flashing you can get 60 hours out of the Sulu, but on constant beam you'll cut that in half. The black aluminum machined housing is secured with waterproofed seals. The integrated rubber quick release will allow you to fasten it onto your seatpost or backpack, whichever you prefer. With a 27mm diameter and 21mm height, the Azonic Sulu CR Rear Light is a compact way to buy yourself some post sunset insurance.