Serfas Thunderbolt 2. 0 Front Light Rear The new Serfeas Thunderbolt belongs to the True Series line of light that Serfas has recently launched, which aims to being the best on the market. They were designed to meet and exceed their expected lumen output. It lights up to 50 lumen and gives you up to 13 hrs of runtime. Features Super Bright (50 Lumens) *Daytime Flash Auto Safe Mode Last Mode Memory USB Remote Switch Compatible Aero Post Compatible USB Rechargeable Specs Solid Modes: High (25 Lumens): 1. 5 hrs, Medium (15 Lumens): 2. 25 hrs, Low (10 Lumens): 5. 5 hrs Flash Modes: *Daytime Flash (50 Lumens): 19. 5 hrs, High Flash Slow (25 Lumens): 9. 5 hrs, High Flash Fast (25 Lumens): 5 hrs, Low Flash (10 Lumens): 13 hrs, Auto Safe Mode Extends Runtime an Additional 45 mins Weight: 40 Grams with Bracket Battery: 500 m Ah Lithium Polymer | Serfas | Thunderbolt 2. 0 Rear Tail Light 50 Lumens