Feature: 1. SMALL DETECTION DEVIATION: Red and green colors are pure and can be filtered completely, red and green colors are complementary, effectively avoiding detection deviation. 2. FUNCTION: Clinical test for ocular suppression and amblyopia, which can determine the type of color vision disorder of the patient. 3. FLASHLIGHT HANDLE: The flashlight in this set of optometry tools has an anti slip design, which is easy to hold and not easy to slip off when using. 4. DISTORTION REDUCTION: The optometry tool comes with color blind clip glasses to help minimize distortion and increase the contrast of all colors. 5. LIGHTWEIGHT: Made from hard, durable plastic, the 4 dot test tools are lightweight and virtually unbreakable. Include the red green glasses, and instructions manual. Specification: Item Type: 4 Dot Red Green Light Glasses Material: ABS Built in Battery: Lithium ion battery 1200mAH Product Function: 1. 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. 2. To determine whether there is visual fusion dysfunction in the two eyes in the case of separation of monocular inhibition at the same time.. Package List: 1 x Four Dot Light1 x Storage Box1 x Left Red Glasses Clip 1 x Instruction Manual1 x Glasses1 x Battery Charger