The battery-operated Ledlenser i4 penlight is only slightly larger than a pen With three micro-cells, the Ledlenser i4 achieves a good lighting performance of up to 80 meters beam distance and a luminous flux of up to 120 lumen. In the lowest setting, it lights for up to 20 hours. Like all penlights in the Ledlenser i-series, the i4 is fitted with the patented Advanced Focus System which enables infinite and precise focusing of the light cone.