The Handheld Red Light Source is an ideal tool for identifying broken or bent patch cord, especially for fiber identification during ribbon or bunched optic fiber pigtail installation, in which identification work for fiber from end to end may cause inconvenience or time-consuming. The Handheld Red Light Source emits a continuous or blinking bright red light at the fault location, which is easily visible through the fiber jacket, for either single mode or multimode fiber cables.