Eye doctors can use this product to take care of every single kind of eye or ocular measurement one requires. It has a level adjustment feature that can move with just one touch by adjusting the leveling knob and level. Also, the interpupillary measurements can go from 48 to 80mm and can be adjusted in 1mm increments. The knobs are on both sides and make it easy for the user to adjust the measurement as necessary to help protect the testing process.