In my country, Indonesia, especially in Jogjakarta, the traffic is so crowd with car and motorcycle. There's only some people who use bicycle for transportation.
When they use bicycle in public road, it's very dangerous to turn left or right without giving any signal. Usually , they look at behind them and wave their hands before they turn.
Waving hands could reduce their balance while on their bike and it possible cause an accident. Therefore, we need mechanical turn signal for bicycle. I design this signal with elegant design and easy to recognize by other driver, so it's very effective and safe. Same at night too