ITEM NAME:5Pcs/set Optical Pupil Distance Ruler Ophthalmic PD Meter Eye instrument Ruler.The pd ruler can help you when you want to buy glasses online. 5pcs/setX Eye Occluder PD Rulers. Quantity: 5PCS. Put the notch over your nose, as close to your eyes as you can, then find the middle if your pupils in a mirror.
