Fibertronics Fiber Optic Loopbacks are designed to return media; this is typically used for testing and network diagnostics. Loopbacks are useful for testing equipment to determine where a fault might lie. These have a very compact design, and like all our products, may be custom ordered to have different lengths, jackets, etc. Our loopbacks are compliant with ATM, fast Ethernet, fiber channel, and gigabit Ethernet, and are available in Multimode and Single-mode. Call or email today to place an order or ask about our additional options.