Definition Of Rapidly|Free Data Visualization|Precision Optical Structure:Features a precise optical structure for clear, accurate pupil measurements. Digital Display & PD Adjustment:Displays measurements digitally and offers a direct PD adjustment lever for rapid, simple operation. Automatic Power-off & Memory Function:Saves power with auto power-off and memory function, ensuring data is not lost. Versatile Viewing Distance Selection:Includes an adjustable viewing distance lever for measuring all types of viewing distances. Dual Eye Measurement Capability:Capable of measuring both eyes separately, ideal for monocular use. Cornea reflection light coincidence method is used; This operates by aligning luminous points on the pupils with the measuring line; Results are displayed digitally in LCD window: Right, PD, Left; Automatic power shut-off in one minute after operation is completed. Range of measurement: 50-80mm(Total) in 0.5mm steps, 25-40mm(Each) in 0.5mm steps Display: Liquid crystal digital display Fixation target: Green dot on illuminated background Focus range: 30cm, 40cm, 50cm, 100cm, 200cm, infinity Illumination: LED Automatical shut-off: after one minute of inactivity Power supply: 3V DC, 2 AA batteries Note: Installation guide not included, we strongly recommend you seek professional installation. Please check as much as possible to make sure the item is what you need. Tips: The product may be updated constantly ,Due To Different Batches, The Actual Product May Have Slight Differences Or Color Differences, Which Does Not Affect Use Color: As shown Material: ABS Package Contents: 1 * Digital PD Meter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.