Designed for military and law-enforcement use, search and rescue, hunting, and outdoor adventures, the Acebeam K40S LED Flashlight offers six brightness levels with a maximum output of 1500 lumens and a defensive strobe. A tail cap push-button switch controls power on a momentary and constant-on basis, while the brightness level is selected by twisting the magnetic ring just behind the light's head. Runtime ranges from 1.5 hours on Turbo to 2000 hours on the 0.5-lumen lowest setting. Built of Type III hard-anodized aluminum, the K40S has a generously knurled handle for a secure and satisfying grip. Heat-sink construction and a copper base plate help dissipate heat from the light's Cree XPL High Intensity LED. The light carries an IPX8 rating for water resistance and is powered by three user-supplied 18650 li-ion batteries.