The Nitecore SENS CR is a small, yet powerful flashlight that uses CR123 batteries. This flashlight by Nitecore features an innovative Active Dimming Technology (ADT) design that offers automatic power saving, in addition to the three levels of brightness for mode switching on the fly. The Nite Core Sens-CR Flashlight features an integrated acceleration sensor and micro processor which work together to calculate the distance of targets based on geometric theory. The sensor continuously detects the angle of the flashlight in relation to the floor, while the micro processor uses this data to vary the light output. Real-world example: Turning the NiteCore Sens CR Waterproof Flashlight on with the head pointed straight up activates active dimming mode. When held in a horizontal position, output will seamlessly and automatically increase for illuminating targets at a distance. Alternatively, when held vertically output will seamlessly and automatically reduce for closer range targets. When used in ADT mode, the flashlight enjoys significantly longer runtimes than competing products. The Nite Core SENS-CR 3-Mode Flash Light is waterproof in accordance with IPX-8 (submersible up to 2 meters), so you don't need to worry about the weather or accidentally dropping it in a puddle.