· For SC, LC, or other fiber connectors: Simply plug the VFL into one end of the fiber cable. Turn on the optical visual fault. When it comes to testing fiber optic cables, a Visual Fault Locator (VFL) is an essential tool in your toolkit. It's a cost-effective and. In the environment of integrated network wiring, in order to meet the needs of high-performance wiring, optical fibers often appear bare fiber, disc fiber, optical fiber splicing, etc. Note: Meant for use with polished, terminated fiber cables. Tool sends visible light over a fiber strand with a 10mW power, good enough to reach. ● Practical Design: Small size and lightweight, pen-type design with pouch make it portable.