[ SMART BRAKE SENSING & EASY to INSTALL ] - Automatically switch to high light mode when braking, ultra-bright for 5 secs lights warning back rider to enhance your safety.You can mount it under the saddle with metal mounting bracket or mount to the seat post with adjustable silicone strap[ SIX LIGHT MODES & HIGH LUMEN LED&PROFESSIONAL LIGHT DESIGN ] - This light is designed for professional cycling enthusiasts, it has an anti-glare lens. The light is clear and not dazzling, and the tail end is a streamlined light design, suitable for use as a pilot light. There are 6 light modes for your choice. enjoy your cycling as you wish, High lumen COB Led bike taillight makes you more visible, it's a perfect bike light for night riding[ AUTO ON/OFF for BATTERY SAVING ] - This Smart bike tail light including Motion Sensor and Light Sensor,it will be auto off when detect in no motion after 30 secs. Once touch it or detect the bike is moving, the light will auto on again. Also when you ride under the sunlight, the tailight will be auto off due to the light sensor is working, IF YOU LIKE TO RIDE IN THE DAYTIME AND NEED THE TAILLIGHT KEEP WORKING ALL THE TIME, Please select the left side and press the General Mode button[ BRIGHTNESS ADJUSTABLE & HIGH LUMEN ] - The brightness of this bike rear light is adjustable, Max to 120 Lumen,1000m Viewable, in the steady on mode, just long press the button to adjust the brightness that you need, it Built-in 400mAh Li-ion battery, it can lasting 50 hours (will be influenced by the brightness that you setting) runing time when fully charged[ UNIQE APPEARANCE DESIGN & IPX6 WATERPROOF ] - We break the appearance of traditional bicycle taillights and adopt a new streamlined appearance structure, which increases the beauty of your overall bicycle, and the streamlined design can reduce wind resistance when riding.