Features: Accurately Tester the effectiveness of your glasses with this set of blue light Tester cards. Ensure your eyes from harmful electronic device radiation. This anti blue light detection card is a pratical tool. The strong the blue light, the deepthe color change, which is convenient to Tester. Suitable for individuals who spend long hours use electronic device, such as students, office worker, and programmers, as well as those concerned about maintaining healthy eyes. 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. Ensure 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. Specifications: Material:Paper Quantity:1Set,5Set (optional) Card Size:Approx.50mm/1.97''x100mm/3.94'' Package Includes: 1Set / 5Set Blue Light Tester note: Please allow 1mm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual color.