Hobbes 258010 FIBERID Fiber Identifier provides a fast and accurate method of traffic testing and identifying optical signals without having to cut or unplug the cabling and interrupt service. Hobbes 258010 FIBERID detects and identifies propagation direction of a signal in fiber to a –40dBm sensitivity at 1550nm and can also trace an optical tone generated by one of Hobbes' OPTISource series units.