A VFL is used to detect faults, breaks, or bends in fiber optic cables by emitting a bright red light that is visible even through the fiber's jacket. It's a cost-effective and straightforward tool, making it ideal for quick troubleshooting and maintenance. If you're new to fiber optics or just. Visual fault locator cable continuity tester locates fibers, finds faults, verifies continuity and polarity. It emits a visible red laser light (usually at 650 nm) through the fiber, helping technicians identify issues such as breaks, bends, and poor splices. It locates fibers, finds. A Visual Fault Locator which can be also called visual fault identifier (VFI), fiber fault locator, fiber fault detector, etc.