Serfas TSL-1200 Just the thought of your headlight battery running low always lurks at the back of your mind. Don't get caught in the dark without a light. The extremely compact Serfas TSL-1200 shines 1200 lumens to guide you on your ride. The external battery pack is a 4 cell lithium ion battery with run times from 3 hours and 40 minutes to as long as 13 hours and 20 minutes. Features Helmet mount Handlebar mount Wall charger Battery attachment strap 4 cell Lithium Ion battery, 5200 mAh Weight: 300 grams with battery Run Times Overdrive 1200 lumens- 3 hours 40 minutes High- 800 lumens- 5 hours 15 minutes Standard- 550 lumens- 7 hours 20 minutes Low 270 lumens " 16 hours 15 minutes Flash- 600 lumens- 13 hours | Serfas Tsl-1200 Headlight Black