Loopback Adapter/Test Plug for network connection verification ^^ Used in Multimode 50/125m Fiber for equipment testing and simulation ^^ Standard Duplex LC Connector ^^ Made of Plastic PEI Shell and Ceramic Sleeve. Insulation is Heat Resistant and Wear Resistant, with Good Stability ^^ Widely Utilized in Optical Fiber Sensors, Optical Fiber Connection and Transmission Equipment, Optical Fiber Communication Rooms, and Optical Test Equipment