This anti blue light detection card is a pratical tool The strong the blue light, the deepthe color change, which is to Tester Applicable in various environment like home, offices, and schools, these Tester cards allow you to easily evaluate the blue light blocking effectiveness of your glasses effective eyecares whenever necessary Improve your eye health with these user friendly glasses Tester cards Stay aware of potential eye strain and enjoy enhances visual comfortable Suitable for individuals who spend long hours use electronic device, such as students, worker, and programmers, as well as those concerned about maintaining eyes Accurately Tester the effectiveness of your glasses with this set of blue light Tester cards your eyes from harmful electronic device radiation, Manufacturer: Tsophreniq