Parameters:
1. Method of measurement: Cornea reflection light coincidence method
2. Effective measurement range: 45-82mm (Binocular pupillary distance),
                                                     22.5-41mm (Left or right pupillary distance)
3. Absolute indication error: ≤0.5mm
    Absolute dissymmetrical error: ≤0.5mm
    Absolute rounding error: ≤0.5mm
4. Distance of target: 30cm~∞
5. Auto-off time: 1 minute
6. Power source: DC 4.2V
7. Weight: 0.8 kg