Serfas Thunderblast 2.0 Front Light One of kind design - the Serfs THUNDER blast alerts riders when the battery is running low. This way, you never get caught in the dark Super bright and Super loud - the THUNDER blast pack 100 lumens of light and 85 decibels that alert you when your battery is running low Easy to mount - extra long silicone mounting straps for endless mounting options including Aero post compatibility USB rechargeable - quickly charges on any USB source in just under 4 hours Chose your Mode - The Thunder Blast offers High and Low beam and 2 flash modes, with run times up to 15 hours (low flash)