Fiberlink 6658 Optical Length Tester offers a unique, low-cost alternative for users who need to measure the length of optical fibers. Fiber installations are increasingly required to have fiber length measurements to comply with bid requirements. Rather than purchase certification test sets that can cost thousands of dollars, the Fiberlink 6658 Optical Length Tester can be added to an installers existing fiber test kit. These length testers use a around-robin method of measuring fiber length. This is accomplished by looping back two fibers at one end of the fiber run with a patch cord. The round trip time that the light takes to travel through both fibers is converted to length in kilometers, then divided by two to show the length of the fiber cable. There is no need to measure the length of all the fibers; the length measurement can be applied to all fibers in the cable. This method of length testing provides accurate measurements, and saves time and money. Measuring fiber by the jacket is an accepted method of measurement; however, there are many scenarios where this may not be valid. Length markings may be hard to reach if they are already terminated ina patch panel. Fiber links may also go through multiple cross-connects or have splices in the middle, thereby making jacket markings invalid. Optical measurement of fiber produces accurate results without the need for jacket markings.