Abstract: A variable beam flashlight has a housing with an exterior control knob that is movable by thumb. A light assembly in the housing includes a casing having a cylindrical guide housing within a bore, the inner surface defining the bore having a helical grove. Within the guide housing is cylindrical bulb extension member in which the bulb is fitted to one end. The bulb extension member has a groove member that extends through a slot in the guide housing and into the helical groove, such that when the control knob is rotated by the thumb, the guide housing is rotated. The rotating guide housing slot displaces the groove member causing the groove member to follow the helical groove. As it follows the groove the bulb extension member is moved longitudinally within the guide housing, causing the bulb to be positioned at variable distances from the front lens.