【Wide Measurement Wavelength Range】10 standard measurement wavelengths: 850/980/1270/1300/1310/1490/1550/1577/1625/1650 nm, testing range: -70 DBM -+10 DBM. 【VFL Function 】The Fiber Optic Visual Fault Locator can detect fiber patch cord faults. Two AAA batteries are required (note: batteries are not included in the packaging). Multiple functions help improve the work efficiency of fiber optic communication personnel. 【Professionalism】The sensitive chip ensures high Measurement Accuracy, with a measurement error of less than ± 0.2dB, and supports user calibration. Durable internal structure, long service life, low battery consumption, and support for continuous use for over 16 hours. 【Intelligence】Supports backlight selection, automatic shutdown and automatic power-off functions. It can store up to 500 sets of data, which can be stored and viewed at any time. 【Easy to Use】Anti fall, small size, light weight, easy to carry, equipped with a hanging rope. Xunsomten - Fiber Optic Tester 3 in 1 Function Portable Optical Power Meter (FC/SC/ST) & Visual Fault Locator & LED Lighting, OPM & VFL Fiber Optic Tester, Range: (-70) dBm ~ (+10) dBm (OPM-VFL-10)