Features DIRECTION IDENTIFICATION: Accurately identify the direction of the optical fiber. When there is a signal from the optical fiber, the left and right direction lights display the signal direction. The left direction light comes on, indicating that the ligh WITH ALARM: Fiber identifier effectively identifies traffic direction and frequency tones (270Hz, 1KHz, 2KHz) with audible warnings. 10KM MEASUREMENT DISTANCE: Built in VFL red light source can measure a distance of about 10 kilometers. ABS MATERIAL: Made of premium ABS material, this optical fiber detector is wear resistant and scratch resistant for long service life. EASY CARRYING: Comes with a small size and a light weight as well, this optical fiber tester can be easily carried around for convenient use. Specification: Item Type: Optical Fiber Identifier Material: ABS Battery: Polymer lithium battery 3.7V 650mAh (shipped with built in battery) Application: Fiber optic identification Basic Parameters: Wavelength Range: 800 to 1700nm Signal Recognition Type: CW, 270Hz ± 5%, 1kHz ± 5%, 2kHz ± 5% Detector Type: Dia. Approx. 1mm / 0.04in InGaAs 2 pcs Adapted Fiber Type: Universal dia. 0.25, dia. 0.9 (for bare fibers), dia. 2.0, dia. 3.0 (for tail fiber) Signal Direction: LED indicator light for left and right direction indication Optical Power Reading Range: -50dBm to +26dBm Display Resolution Linear Display: 0.1%. Logarithmic Display: 0.01dBm Optical Power Meter Wavelength Range: 850 to 1650nm Use Distance of the Red Light Source: Greater than Approx. 10000m / 32808.4ft Working Temperature: -10 to +60 ℃ Storage Temperature: -25 to +70 ℃ Package List:1 x Optical Fiber Identifier1 x Manual   1 x USB Cable  1 x Storage Box   Package List 1 x Optical Fiber Identifier 1 x Manual 1 x USB Cable 1 x Storage Box