The UT691 series red laser pointer uses a 650nm semiconductor laser as the light-emitting device, driven by a constant current source, emitting stable and highly penetrating red light. After connecting with the optical fiber interface, it enters single-mode or multi-mode optical fibers to achieve the function of optical fiber fault detection. In terms of design, it is mini and compact, easy to carry around, and equipped with a hanging hook to prevent dropping. It also comes with an LED lighting lamp and various working indicator lights, allowing you to work easily even in dim environments.