1VFL Red Light Pen: This red light pen is specially designed for the design and maintenance of fiber optic cables and lines to locate defects on cables and cables. 2Non Contact Connection: This connection is non destructive to the fiber and the end face of the transmitter, and the output power is not affected by voltage fluctuations. 3Stable Output: The fiber optic pen has stable output power, the output distance is 50km, which is a good tool for fiber testing. 4Small and Portable: The fiber optic pen is small in size, light in weight, energy saving, and easy to carry for outdoor work. 5Aluminum Alloy: The aluminum alloy shell of the positioner is corrosion resistant, rust proof, and resistant to falling and wear, providing a long service life for the positioner.