Splitting the difference between the previous Flux 800 & 900 the Flux 850 gets the game-changing Mode Shift found on the Flux 1250. This means there are three steady modes all using both the wide & spot beams. Go from Steady Low to Steady High in a single push without cycling through a flash mode. Press-&-hold for two seconds & you get into the secondary modes: Steady Flash to be seen in busy urban environments Flash Mode for endless runtime & two Flashlight modes with 10 & 20 hours of runtime for hanging around the campsite or when you forget to charge your light & need to conserve the last few percent of battery life to get home. IPX7 waterproof means this light can survive being submerged 1 meter deep for 30 minutes. No its not meant for scuba diving. But is can handle anything you can throw at it on two wheels. Sculpted double beam pattern uses separate optics for wide & spot beams to put light where you need it & maximizes every lumen. The result is a beam pattern that torch-style lights cant touch. 1x CREE XP-L High Intensity LED plus 1x CREE XP-G LED. Quick-release bar mount works on 22.2 25.4 & 31.8mm bars to put the light above below or in front the stem to clear cables & computer mounts. Extra bright side lights to give you 180-degree visibility to other cyclists & motorists. 2600m Ah Li-ion internal battery is USB (Universal Serial Bus) rechargeable via included micro USB (Universal Serial Bus) cable. Depending on mode up to an additional three hours of super-low output are available when listed runtimes expire. Trust us someday youll need this. Steady High mode: 850 lumens for 1:30 hours Steady Medium mode: 450 lumens for 3:00 hours Steady Low mode: 250 lumens for 6:00 hours Press-&-hold to turn off long press-&-hold to enter secondary modes. Steady Flash mode: 300 + 200 lumens for 4:00 hours Daytime Flash mode: 400 lumens for 20:00 hours Very low mode: 100 lumens for 10:00 hours Super low mode: 50 lumens for 20:00 hours Extra-long press-&-hold to lockout light for travelling.