High Lumen Tail Light: This rear bike light uses a COB light source to deliver a powerful, bright beam with a wide 180-degree visibility angle The added daytime strobe function ensures you're highly visible to other road users, keeping you safe on every rideSmart Brake Sensing: This bicycle tail light automatically brightens when you brake for added safety; Built-in sensors turn the light on when you start riding and off after 30 seconds of inactivity; A single click activates manual mode, and in manual mode, press and hold to turn the light on or off4 Light Modes & Safety: Customize your rear bike light with 4 lighting modes: Constant Light: 20 hours ,Quick Flash: 50 hours, Slow Flash: 40 hours , Strobe Flash: 40 hoursEasily switch between modes to suit your needs and different riding conditions for the best visibility and safetyLong Battery Life & IPX5 Waterproof: Equipped with a safe, USB-C rechargeable 400mAh polymer lithium battery, this LED bike light offers up to 50 hours of runtime; With an IPX5 waterproof rating, its built to withstand all weather conditions, ensuring reliable performance rain or shineEasy to Install & Versatile: No tools required; Simply mount the red rear light to your bikes saddle bracket or seatpost and secure it with the bracket This light is also perfect for attaching to wheelchairs, strollers, pet harnesses, kidsbikes, backpacks, and more