Features 1. Elegant design of butterfly-shape appearance 2. Capable of checking up all-sided visual functions, precise and comfortable in measurement 3. Exquisite manufacturing technique, with comfortable feel 4.This device is applicable to ophthalmology department of hospitals and spectacle stores for precision measurement of visual functions such as myopia, hyperopia, astigmatism, eyesight balance, heterophoria, stereoscopic vision and eyesight amalgamation 5.Three color options:White or Blac