LY-A12D Digital Lens radian clock

Index Range: N:1.49/1.53/1.56/1.599/1.61/1.67/1.71/1.74
Technical Parameters:
1) Measuring Scope: ±2000
2) Resolution: 25  
3) Power Supply: 3V（LR44/SR44 Two 1.5V button batteries）
4) Operating Temperature: -10～50℃  
5) Storage Temperature: -20～70℃
6) Operating Humidity: ≤80%
Instructions:
A) “ON/Z”  
    1) short press to turn on/off，auto power ON/OFF.  
    2) Long press 2-3 seconds to set to zero  
B) “U”   
    1）short press to switch the relative refractive index: 

1.49 →1.53→1.56→1.59→1.61→1.67→1.71→1.74
    2）Long press for 3 seconds to restart.
C) “CALC”: Calculate the curviness of lens.
    1)Measure the one side of lens and press “CALC” to record the data, when “CALC+” or “CALC-” flashes, measure the other side.
    2)Press “CLAC” to measure the other side, undo “CALC”
    will display the final actual degree of lens.
    3)Short press “CALC” and display “----” to exit. Measure other lens when “CLAC” disappear.
D) Auto power on/off
    Auto power on in 1 second after moved the measuring point
    Auto power off when the measuring point static for 1 minute.
E) Low battery warning: when the batteries under 2.3V, it will flash the battery symbol, and please replace batteries.
CAUTIONS:
1)  First use or after replace the batteries, please long press button U to restart the gauge, and avoid to touch the measuring point.
2)  The gauge has factory settings, no need to set to zero if the measuring point hasn’t been adjusted. When it is a large numerical error, please try restart the gauge, if failure, then reset it.
3)  When replacing the batteries, please replace both at the same time, to preserver battery life.