Product details:

NiteRider's Sentinel 40 USB Tail Light is not only a bright rear light but it also features innovative ultra-bright laser emitters that project a virtual bike lane on the road to give traffic a better idea of how much space to give when passing. This USB rechargeable light features 7 modes between the blinky and lasers for up to 36 hours of use plus a battery indicator that gives an approximation of remaining charge each time the light is turned off. The main blinky puts out a strong 40 lumens but a special Group Ride Mode lowers the output so trailing riders don't get blinded. Claimed weight is 73 g. Rechargeable using the included USB cable.