Tegg PD Ruler Optical Vernier Pupillary Distance Meter Eye Ophthalmic Tool

Matters needing attention in measuring interpupillary distance: 1. Keep your eyes squarely ahead and look at the still life about 20 meters away (If you are in a house, look into the distance), Do not turn your eyes during the measurement. 2. Do not measure in the mirror by yourself, Please ask family or friends to help with the measurement. 3. Please start the calculation from the 0 degree scale of the ruler, Do not start counting from the edge of the ruler. Measuring range: 0-100mm Material: PVC Color: white color Size: about 21x5x0.7cm / 8.26x1.96x0.27Inch (LxWxT).