1、ADJUSTABLE PUPIL DISTANCE: The pupil distance of this red green blindness vision trainer is adjustable, with an adjustable range of 1.7-3.3in and can be used by both adults and children. 2、STURDY: The slide of the flip shot is stuck relatively tightly, and will not slide when flipped up and down, which can firmly fix the adjusted pupil distance and is not easy to loosen. 3、SCOPE OF APPLICATION: Color blindness tester is very practical to use and can help you test color blindness and color weakness, suitable for second level visual function check. 4、PLACE OF USE: Color blindness evaluator can improve visual clarity and make your eyes more comfortable, suitable for optometry places, optical stores, etc. You can also do vision training at home. 5、THE BEST GIFT: You can give this red green color blindness vision improvement trainer as a gift to your family, friends and colleagues who have color blindness symptoms. Item Type: Color Evaluator Lens Material: ABS Scope of Application: Second level visual function test, color blindness and color weakness test 1 x Color Evaluator Lens 1 x Instruction Manual 1 x Lamp Sheet