Smart Brake Sensing With brake sensor inside,this smart bicycle light will automatically light up bright brake light after you braking.The bicycle light is more bright at that time and highly visible even from a distance,attract the attention of bikes and vehicles behind to enhance your safety while cycling.Auto/Manual ModeSwitch the mode by pressing the middle button twice. In automatic mode,when the bicycle stands still for ten seconds,it will go out automatically.It will light up again when you start riding.In manual modeit will only light up or go out under your control.Easy Mount and RemoveSmall Size and Light WeightSaddle mounting bracket and adjustable silicone strap are provided,make the bicycle rear light quick and flexible install on saddles,seatposts,bike bags.Battery Life up to 30 HoursIPX5 WaterproofThree light modes: constant light mode(10 hrs),breathing light mode(15 hrs) and flashing mode(30 hrs).There is a indicator to remind you battery is low.The taillight can be easily charged by charging cable via computer,wall charger,power bank or any other devices with an USB port.IPX5 water resistant,ensure your safety ride in bad weather condition and environment.Run TimeFlash mode>30hrs,breath>14hrs,Constant>10hrsBattery Capacity400mAh rechargeable Lithium-ion batteryNet Weight31g (Saddle mount),36g (Seat post mount)Dimension36mm X 29mm X 26.5mmBrightness30lmMaterialAluminium alloy,plasticConnectorUSB microWater ProofIPx5Packing List1x Cubelite II bike light1x saddle mount1x seatpost mount4x zip tie1x user manual