Feature: 1. Avoid Deviation: 4 Dot vision test light with red and green lens, pure and complementary colors, which can effectively avoiding detection deviation. 2. Usage: 4 Dot optometry test light can be used for ocular suppression and amblyopia, and determine the type of color vision disorder of the patient. 3. Wide Application: Ophthalmic 4 dot test light can improve the clarity of vision, which is suitable for optometry places, optician shops and so on. 4. Color Blindness Test: With a flip turner, simple and practical to use, you can adjust the pupil distance, help you test color blindness weak. 5. Excellent ABS: Four light test red green glasses are made of ABS material, firm and sturdy, not easy to be broken and can be used for a long time. Specification: Item Type: 4 Dot Vision Test Light Material: ABS Battery Type: Lithium Ion Battery 2000mAH(Included) Function: Wearing red and green glasses to observe the four dot light, the use of color complementarity of this situation, the separation of the two eyes. Determine whether there is monocular inhibition of simultaneous vision and blend vision in the separated eyes.. Package List: 1 x 4 Dot Light1 x USB Cord 1 x Instruction Manual 1 x Flip Tool1 x Glasses1 x Red Lens1 x Green Lens