We all have had close calls when group riding. The leader has to make an emergency stop and then next thing you know there's an accident. What if there was a light that turns on when someone slows down. But that would add bulky wiring and the need for an extra battery to have a brake light. You don't need all that anymore. With our smart light you can have a brake light now, it uses the changes in acceleration or deceleration to turn on and off a light notifying every behind you that you are slowing down. Not only does is have the brake light feature, it has an automatic on/off mode. When you dismount your bike and leave it stationary, the inbuilt flashing light will turn off. Just jump on your bicycle to start the flashing light again. It can either be mounted to the saddle or to the seat post.