The X-Power 850 is a great do it all light, being able to give you 850 lumens for 2 hours for you night ride, or step the mode down to standard and get 4 and 12; hours of 400 lumens for your ride to and from work. If you are after a high power bike light that you can use for all aspects of cycling, then the X-Power 850 is the light for you. Features: 2 Cree XM-L (T5) high brightness LEDsCNC aluminum alloy body7 modes : Over drive / High / Standard / Low /Flashing / Strobe / SOSQuick release rubber strap mount (fits 22-31.8mm )Quick release helmet mountOver heat protection systemLow battery indicatorPrecision optical lensRechargeable lithium ion battery (7.4V 2600mAh)Smart charging (100-240 volts) with fully charged indicator and automatic fully charged cut-off systemSize:46 x 47 x 22 mmWeight: Light body 80g / Battery case 196gRun TimesOver drive Mode - 850 Lumens Output - 2 hours runtimeHigh Mode - 600 Lumens Output - 2 hours 40 mins runtimeStandard Mode - 400 Lumens Output - 4 hour 30mins runtimeLow Mode - 180 Lumens - 9 hours 40 mins runtimeFlashing Mode - 8 hours runtimeStrobe - 7 hours 40 mins runtime