Feature: 1. Application: This optical light source supports 1310, 1490, 1550nm wavelength, powerful, mainly used for FTTX network and fiber testing. When combined with an optical power meter (not included), it is used to measure optical power end to end optical loss. 2. Universal Interface Design: Handheld optical light source, stabilized light source with 2.5mm universal interface for a wide range of applications. Interface with silicone dust cover, to guard the interface from damage, longer service life. 3. 4 Modulation Frequencies: The fiber optic light source has 4 output modulation frequencies (CW, 270Hz, 1kHz, 2kHz) at 1310, 1490, 1550nm wavelengths for stable and reliable output. 4. Backlight And LED Light Design: LCD screen with backlight display for viewing in dark and low light environments. And it is equipped with one LED light, which can be used normally under darkness and improve working efficiency. 5. Drop Resistant And Portable: Made of premium materials, shockproof and drop proof, reducing collision damage and extending service life. Compact size, perfect for measuring on the go, providing convenience and mobility for professionals. Specification: Item Type: Fiber Optic Light Source Material: ABS Product Size: Approx. 130 x 35 x 65mm / 5.1 x 1.4 x 2.6in Wavelength: 1310nm, 1490nm, 1550nm Output Power: ≥-5dBm Optical Connector: 2.5mm Universal Power Supply: 2 x AAA Battery (Not Included) Output Stability: ±0.05dB/15mins; ±0.1dB/8h Modulation Frequency: CW, 270Hz, 1kHz, 2kHz. Package List: 1 x Fiber Optic Light Source1 x Instruction Manual Download Guide Note: Manual measurement, please allow some errors.