Smart Light Sensing: Built-in light sensor and vibration sensing work in coordination, smart start and stop to save power.Adopt high-sensitivity smart sensor chip to correctly detect vibration and braking action.Visibility at night is high but not dazzling, SOS and Bright modes are manually controlled and not affected by sensing elements.Multifunctional Security Light: Easy to install. Lightweight and durable bike tail light that can be mounted on all bikes, kids bikes, adult bikes, handlebars, seatposts, dog collars or anywhere. It can also be used as helmet light, backpack light, warning light, etc.Set your own light mode: 7 light mode options, there are 3 flashing modes, 3 brightness, 1 breathing light You can switch different modes according to your needs and different occasions to get the best lighting experience.NO BATTERIES NEEDED: This bike tail light has a built-in USB charging port (USB cable included). Please charge when the indicator light is red. Turns green when fully charged.Waterproof Bicycle Tail Light: The tail light is made of IPX6 rated waterproof material to ensure safe use in heavy rain.The tail light has 2 working modes: Power on and click the button to switch to automatic induction mode; Press and hold "3 seconds" to enter manual mode.Style: B: seat post typeColour: black+redMaterial: aluminum alloy+ABSSize: 110x80x34mmPackage Contents:1 set * Bicycle tail light intelligent brake sensor lightOnly the above package content, other products are not included.Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.