The Gemini Xena offers the lightweight (55g) head unit throwing an impressive and wide beam of 950 lumens and the option of 2 or 4 cell lithium batteries. Choose the Xena if you prefer a helmet mounted light without the weight and the longer run time at full power or stock multiple charged batteries for extra long running requirements. Lumen Output: 950 Run Time: 2:00 – 17:00hrs Small size. Incredible power. At 950 lumens, the Gemini XERA LED Bike Light means serious business in the high-power light category. Driving this powerhouse is a single CREE XM-L2 U4 LED emitter – the most efficient, high power LED on the market. The Gemini XERA is both lean and mean, weighing in at just 55g – fit for racing and fit for you. Adjustable beyond low, medium, high modes. There are ten brightness levels between 10-100% for your Low, Med, High and Flash modes. Each mode is programmable so you can to adjust your Low, Med, High and Flash modes to your own liking. Fine tuning your power levels allows you to take full control of your runtime. By default, the XERA is set at Low 20%, Medium 60%, High 100% and Flash 60%. To reset your modes back to these factory settings, hold down the button for 10 seconds. Handlebar and helmet mount included. A handlebar and helmet mount are bundled in the XERA Light Set for your night time activities. Use the silicone o-ring to mount the XERA onto your handlebar or your helmet. A head strap is also available as an optional extra.