xanes® stl15 smart brake sensor tail light bicycle back waterproof safty road bike cycling motorcycle

features: 1. automatic intelligent mode: brightness sensing + motion sensing: the ambient brightness is low, the tail light is bright; the ambient brightness is low, the tail light is off; the ambient brightness is low, the riding becomes static, the tail light is off after 1 minute; the ambient brightness is high, the tail light off; the ambient brightness is low and high: the tail light is off after 1 minute of riding.