LY-18 DIGITAL PD RULER

With its small size, the net weight is only 200g.
Simple and efficient measurement method.
The digital PD ruler uses a 23A 12V battery, which is easy to replace at the backside.
Automatically powers off when lying down after operation; powers on automatically when picked up.

Steps of measuring PD

1. The person being measured should sit facing the operator and look into the distance.
2. The operator should hold the digital PD ruler correctly and place it carefully on the person's nose.
3. Adjust the two needles to align with both eyes' centers of the pupil. The number displayed on the LCD screen is the PD value.
4. Press the left black button to display the left PD and the right black button for the right PD.
5. Repeat steps 2 and 3, measuring three times to obtain the average value.