Product Description: Quantity: 1pc Color: blue There is chromatic aberration DIY self-calibration: Press + REF + UNIT at the same time to enter the user mode screen, the letter "CAL" is displayed, press the "REF" and "UNIT" buttons to restore the power meter to the factory state Easy to use: Press and hold the UNIT button for 3 seconds to open the RJ45 test mode, then press to close the RJ45 test mode Memory function: Optical fiber tester added wavelength memory function , and the test wavelength setting before shutdown is remembered after shutdown LED: Optical power meter added LED night lighting to facilitate the construction of cables under dark conditions Protection: The rubberized shell protects the optical power detector from damage caused by accioral drops