Nano Duo is a small rear warning system with both brake light and rear light functions. The light signal is the same as other vehicles to let message easier to be understood. The brake light function is controlled by mechanical interaction and could feed back the correct message immediately to the drivers behind you. It works independently no matter the rear light mode is on or not. Nano Duo could be installed on any kind of cable-actuated brake system. With a special designed cap, the light would be noticed easily by the side.