The Moon Sirius intelligent rear light is constructed from a CNC Aluminium heat sink casing equipped with break & light-sensitive technology, meaning it works like a car light. The case features a built-in reflector making it highlight you even when it's not turned on. Day flash Mode, light memory mode & side visibility make it easy to stay safe. USB (Universal Serial Bus)-C rechargeable & Quick release universal bracket add perfect elements of convenience. Features Intelligent operation: Motion-sensitive & Light sensitive Reflection (built-in reflector) Break Sensor Auto safe mode (Around 1hr) Day flash mode Light mode memory CNC Aluminum heat sink casing USB (Universal Serial Bus)-C rechargeable Quick release universal bracket 2 O-rings for mounting:RS-G (fits 20-35mm diameters)RS-H (fits 35-52mm diameters) Low battery, charging & fully charged indicator Automatic fully charged cut-off system Side visibility Water resistant (IPX 7)STANDBY TIME: 500hrs Variable lumen system FL-1 tested lumen FL-1 tested runtime Mode: Output, Runtime DAY FLASH: 150lm, 13hr MODE 1:30lm, 2.4hr MODE 2: 60lm, 1.2hr FLASH 1: 30lm, 14hr FLASH 2: 60, 11hr This light is great for commuting if you want something that's for long rides Consider the Pro version