Abstract: A pen light comprising a hollow substantially cylindrical housing having a retainer member secured to the rear portion thereof to house a single voltage source in operative engagement with a light source, a first conductor member movable between a first and second position and a second conductor member each disposed within the hollow substantially cylindrical housing to operatively engage the light source and the voltage source respectively and an actuator clip attached to the hollow substantially cylindrical housing movable between a first and second position to selectively engage the first conductor member such that when the actuator clip is in the first position the first conductor member is separated from the second conductor member to form an open circuit and when the actuator clip is in the second position the actuator clip engages the first conductor member to move the first conductor member from the first position to second position whereby the first conductor member engages the second conductor membe