Features Plug and Play: This optical power meter has no need to wait for warm up, plug and play, very convenient to use! Accurate Measurement: This meter features accurate measurement, relative power calculation, and calibration function. Long Service Span: This is a low battery consumption meter that it can realize 100 hours of continuous operation. Scope of Application: This meter can detect 6 standard wavelengths and light sources. 850, 1300, 1310, 1490, 1550, 1625. Covering most requirements of communication engineering maintenance. Easy Carrying: Comes with a compact size and a light weight as well, you can easily take this meter with you to help with your work. 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 Joint Type: for InGaAs Accuracy: 0.35dB ± 1nw Operating Wavelength: 800 to 1700nm Continuous Working Time: 100h Standby Time: About 230h Power Supply: AAA battery x 2 required (shipped without battery) Package List:1 x Optical Power Meter1 x Storage Box 1 x Manual Package List 1 x Optical Power Meter 1 x Storage Box 1 x Manual