Features1Avoid Deviation: 4 Dot vision test light with pure and complementary red and green colors, can be filtered completely, effectively avoiding detection deviation. 2Usage: 4 Dot optometry test light is suitable for ocular suppression and amblyopia, which can determine the type of color vision disorder of the patient. 3Reduce Distortion: Ophthalmic 4 dot test tool comes with color blind clip glasses to help minimize distortion and increase the contrast of all colors. 4Function: Wear red and green glasses to observe the four dot light, determine whether there is monocular inhibition of simultaneous vision and blend vision. 5Excellent ABS: Four light test red green glasses are made of ABS material, firm and hard, sturdy and durable, which is not easy to be broken and can be used for a long time.SpecificationItem Type: 4 Dot Vision Test LightMaterial: ABSBattery Type: Lithium Ion Battery 2000mAH(Included)Product 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 List1 x 4 Dot Light 1 x Glasses 1 x Left Red Glasses Clip 1 x Right Red Glasses Clip 1 x USB Cord 1 x Instruction Manual