It sends a visible 650nm wavelength red laser light through a fiber optic cable to identify fiber cable faults (breaks, bending or cracking, pinched, or poor connections) by refracting the light and illuminating the faulty area. VFLs typically use a 650nm wavelength red laser that is transmitted through the fiber. When there are breaks, bends, or poor connections in the fiber, the red light leaks out at. A fiber visual fault locator pen VFL for fiber optic installation, fault finding, continuity checking, polarity checking, verifying a signal path, and identifying a fiber. Always insert and remove the fiber connector without bending the connector to avoid breaking. The Visual Fault Locator (VFL) Pen has a visible red light source centered on 650nm. Tool sends visible light over a fiber strand with a 10mW power, good enough to reach distances of up to 10Km.
