Features a Cree XR-E R2-WC LED emitter - 200 lumens (manufacturer rated) - Voltage input: 3.6V~8.4V - 1100mA digitally regulated LED driver circuitry - Built-in 3 modes + 0~100% brightness adjustment: Lo (250mA40LM) > Mid(600mA90LM) > Hi (1100mA200LM) - Bezel diameter: 26.5mm - Brass base diameter: 19mm - Height including support spring: 36.7mm - Height excluding support spring: 28.8mm - Aluminum textured reflector . - To enter the "hidden" (0%~100%) brightness adjustment mode: continuously switch mode within a 1 second period. The light will slowly begin lighting up from dim to bright. When the desire brightness is reached switch the light off to save the setting. The next time you turn the light on it will stay in the selected brightness. . There are two brightness markers: while the light is slowly lighting up in the hidden mode it blinks twice at the 5% 50% and 100% brightness points to let users know of the exact percentage output.