Smart Auto ON/OFF - The "Slow Flashing" and "Breathing" modes are intelligent automatic modes. After the bike back light is turned on for 30s, the brightness of the riding environment is automatically detected. When it is bright, it will automatically turn off and when it is dark, it will automatically turn on. If you need the bike tail light during the day, you can choose Blinking / Steady Light mode. (These two modes do not have intelligent auto on/off functions) 2 Installation Methods - Equipped with 2 installation methods: Bracket install and zip ties install. The bracket installation is suitable for bicycle pipes with a diameter of 1 "-1.3". If the diameter of the bracket is not suitable for your frame diameter, you can choose to install it with zip ties. Bicycle Alarm and Vehicle Search Function - This bicycle rear light has a bicycle horn and vehicle located ringing function. There are 3 ringtones to choose from, and the bicycle can be easily located in the parking lot from a distance through a loud 110 dB ebike alarm. Rear Bike Light Rechargeable - This bicycle lights can be charged using the included USB-C charging cable. Charge and activate before use, which can be used for about 1-3 months when fully charged. 110 dB Bike Alarm Function This bike lights for night riding has a bicycle alarm system and a 7-level adjustable vibration sensitivity. When the "Arm button" is pressed, the bicycle enters the anti theft state. When someone touches, moves your bike, or tilts the body, the cycling lights for road bike will immediately sound the alarm for 2 seconds. If vibration or movement is still detected within 2 to 12 seconds, the alarm will sound for 30 seconds.