LBTEK Fiber Optic Red Light Pen (also known as a pen-style visual fault locator or fiber optic fault detector) uses a 650 nm semiconductor laser as the light-emitting device. Driven by a constant current source, it emits a stable red light. It is compatible with FC/APC and FC/PC interfaces and connects to the fiber optic interface to perform fiber optic fault detection functions, including checking fiber connectivity and locating fault points such as fiber breaks and bends. Additionally, it can be used for fault inspection within the OTDR dead zone, end-to-end fiber identification, and optimization of mechanical splice points. Two AA batteries are included with purchase.Precautions for using the Fiber Optic Red Light Pen:1. Laser light is harmful to the eyes, so avoid direct exposure of the laser to the eyes when using the red light pen;2. When using the fiber optic red light pen, it is best to clean the fiber optic jumper interface with a cleaning tool;3. Typically, lasers operating in high-temperature environments have a shortened lifespan, so the red light pen should be kept away from high-temperature working conditions;4. After use or when the red light pen will not be used for an extended period, put on the dust cap promptly to avoid contamination from dust, oil, etc.;5. To prevent battery corrosion from damaging the red light pen, remove the batteries promptly if the pen will not be used for a long time.