Specifications: Emitter: 4*Nichia 519A 5000K Operating voltage: 3.0V-4.2V Beam Angle: Narrow beam 32°; Flood beam 86° Battery options: 1x 21700 lithium-ion battery (included) Dimension: 122mm (length) x 35mm (head diameter) Weight: 108g / 0.24lb (excluded battery) Reflector: TIR lens Circuit Type: Boost constant current driver Flashlight body: Aerospace grade 6061 grade aluminum alloy, CNC manufactured to hard anodized to military grade specification type III, anti-abrasive finish to get solid built body, anti-crash geometry and better heat exchange. Water resistance: IPX8 Reverse polarity protection to protect against improper battery installation. Advanced Temperature Regulation (ATR) technology: ATR automatically reduces the brightness level when the driver temperature reaches 60°C to prevent overheating Low voltage warning