Can choose 6 kinds of wavelength: 850nm. 1300nm. 1310nm. 1490nm. 1550nm. 1625nm. Support three kinds of interface:FC, SC, Outgoing maintenance only one machine; Function upgrade 3 in 1 Optical Power Meter + Visual Fault Locator + Network Cable Test DIY self-calibration; According to the actual test needs self-test parameters At the same time press the λ + REF + UNIT button,enter the user mode,the screen displays the letter "CAL" Press the "REF" and "UNIT" keys at the same time to restore the power meter to the factory state Button UNIT,reducing 0.05dB Press the power button.Save Press REF + UNIT:restore factory settings Press the key λ to switch the wavelength Press REF,increase 0.05dB Set the current test result as a reference value,make relative power measurement,the display will show the set DBM Detector type:InGaAs Measuring range:-70 to +3 Uncertainty:± 5% Display resolution:linear display,0.1% logarithmic display:0.01dBm Red working wavelength:650nm Red power:more than 5mW Operating temperature:-10 ~+60 ℃ Storage temperature:-25 ~+70 ℃ Automatic shutdown time:10min Battery continuous working hours (h):more than equal 48 Product Size:118 x 68 x 30mm Power:1.5VAAA x 2(Not included) colour:yellow Material:plastic Package Contents: 3 x Optical Fiber Tester 3 x network cable port Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm. Operation method: Long press UNIT key for 3 seconds to open RJ45 test mode, then press to close RJ45 test mode Cable test function new LED lighting features for dark work environment High quality Penetrating farther, longer life.