1. Accurate measurement, high measurement accuracy and resolution of backlit LCD display, with user self-calibration function. 2. Fast response and measurement. When the output power changes, it can display fast tracking and real-time measurement of optical power. 3、Wide measurement range, can provide 80dB optical power measurement range, absolute optical power measurement and relative power measurement. 4、Six calibration wavelengths: 850nm, 1300nm, 1310nm, 1490nm, 1550nm and 1625nm. 5、Easy to use, real-time monitoring and battery power display When the battery power is low, a warning notification will be displayed and an automatic shutdown function will be displayed. 6、The handheld fiber optic tester requires 3 AAA batteries (not included), has a long battery life, and is practical to carry and use and is very convenient. Item Type: Optical Tester Material: Plastic Product Model: TL510 dBm Measuring Range: -70 to +10 dBm (the optimal measuring range is actually -65 to 0 dBm)