The FCD-10 Fiber-Optic Clip-On Device is a temporary coupler used to connect a fiber-optic instrument to a 250-µm singlemode fiber when access to the fiber end is not possible (best results with clear coated fibers). It essentially consists of a bidirectional coupler. Light is injected in and collected from the fiber by way of a gating bending the fiber to tap the signal. This process does not damage the fiber. The FCD-10 coupler device has many applications in testing and communicating when access to the fiber end (i.e., at the patch panel) is not possible. The device is used to gain access to the signal for connection to test equipment, for instance near a splice tray. It is also used to inject signals into a fiber which terminated in a receiver or to gain voice communication from any point along the fiber via a fiber talk set.