Features Precise Measurement: This meter features accurate measurement, relative power calculation and calibration function. Plug and Play: This optical power meter has no need to wait for heating, plug and play, very convenient to use! Scope of application: This meter can detect 6 standard wavelengths and light sources. 850, 1300, 1310, 1490, 1550, 1625 Covering most communication engineering maintenance requirements. Easy to carry: Comes with a compact size and light weight too, you can easily take this meter with you to help with your work. Long service time: This is a low battery consumption meter that can realize 100 hours of continuous operation. Specification: Item Type: Optical Power Meter Mode: TL537A Material: ABS Power measurement range: - 70 to +10dBm (at 1550nm) Standard wavelength: 850 1300 1310 1490 1550 1625 Gasket Type: for InGaAs Accuracy: 0.35dB±1nw Operating wavelength: 800 to 1700nm Continuous Working Time: 100h Standby time: about 230 h Power supply: 2 AAA batteries required (shipped without batteries) Package List: 1 x Optical Power Meter 1 x Storage Box 1 x Instruction Manual Package List 1 x Optical Power Meter 1 x Storage Box 1 x Manual