Serfas BAT-4 Battery True Series lights offer the highest Lumen outputs and the best-in-class price points The industry's most technologically advanced safety lights All lights are robs compliant and all testing is done in house More efficient leds & high quality lenses to increase brightness & Clarity 6600 mAh for light 13,200 mAh USB Output Li-Ion Battery Pack Fits Serfas Light Models: TSL-T1000, TSL-2500, TSL-POLICE, TSL-1000+, TSL-1500+, BAT-ADT (adapter for True 350, 550 and 750) Integrated USB output is perfect for charging your smartphone, other USB rechargeable light, GPS, etc