FEATURES:1, Host built for grip: Small squared texture milling for a perfect grip and feel. 2, Three-color power level indication: Once the light is turned on, the power indicator located in the center of the side switch shows the power level in three colors (Green: Power>70%, Red: Power is between 30% and 69%; Red flashes: Power<10%).3, Premium beam: Perfectly balanced hot spot for optimal clarity and a soft transition to maintain comfortable vision during use. 4, Comfortable Light Beam: 5000K LH351D LED used, the little yellowish light beam reflexes your eyes in darknessSPECIFICATION: *Light Source: High Performance NW LED LH351D* Dimensions：Length 73mm * Body Diameter 22.5 mm*Weight: 39g (Not including pocket clip or battery) *Body Material: Aluminum Alloy* Battery Power: 1 x 16340 battery (please choose SC21 set if you also need 16340 battery)CR123A battery can only be used for emergency due to the low brightness caused by 3V low voltage.OUTPUT and RUNTIME Mode 1: 1000 LM---1 hrMode 2: 400 LM---1.5 hrMode 3: 100 LM---4 hr Mode 4: 10 LM---18 hrMode 5: 1 LM---85 hrStrobe: 1000 LMSOS: 120 LMBeacon: 1000 LMRamping: from 1 LM to 1000 LM*Max Beam Intensity (cd): 4533* Max Beam Distance (m):135*Waterproof :IPX8 (underwater 2 meters, cannot be usd as diving flashlight underwater) *Impact Resistance(m):1 meterOperation InstructionsGroup 1: Stepped mode groupStepped modes give you fixed brightness levels to choose from: Low – Medium – High, hidden Moonlight and Turbo. From OFF single click to turn ON. Press and hold to cycle through stepped modes (Low – Medium – High). Single click to turn OFF.Double click to activate Turbo mode from OFF or ON. While in Turbo mode, single click to return to the previously used mode, double click again to activate Moonlight mode.From OFF, hold 1 second to turn on with Moonlight mode, another hold to Low.Group 2: Ramping groupRamping mode gives you full flexibility to adjust brightness steplessly from Moon to Turbo level.From OFF single click to turn ON. Press and hold to change brightness steplessly (“ramp”). Ramping changes its direction when the button is being pressed again within 1.5 seconds. The light flashes once when it reaches the lower or upper end of the ramp. From ON single click to turn OFF again.Double click to activate Turbo level from OFF or ON. Another single click to return to the previously used brightness level, double click again to activate Moonlight level.From OFF, hold 1 second to turn on with Moonlight level.Toggle between Group 1 and Group 2From ON, 4 fast clicks to cycle between both mode groups.Strobe Modes Triple click to activate Strobe mode from OFF or ON. While in Strobe mode, single click to return to the previously used standard mode, or press and hold to cycle through SOS - Beacon - Strobe.Electronic LockoutSC21 comes with a lock-out function to prevent accidental activation, e.g. in one’s pocket or backpack. From OFF, 4 fast clicks to activate lockout. Another 4 fast clicks to deactive lockout again and return to the previous mode setting. When the light is locked, the main LED only blinks two times to show the status of being locked. While in lockout mode, hold the side switch to use Moonlight mode.