A professional test book, which is a simple and accurate for discovering congenital color blindness and red-green blindness, each in two forms, complete and incomplete. It includes four special plates for tests to determine the kind and degree of defect in color vision. Makes use of the peculiarity that in red-green blindness, blue and yellow appear remarkably bright compared with red and green. Color plates encased in specially designed album-type books for ease of handling. Detailed instructions included. Individuals with color vision defect should see a different figure from individuals with normal color vision. Please note: the physical slightly color difference or difference, does not affect the use, please do not mind, thank you! Colour:Photo Color Material:Paper Package Contents: 1 x Color Blindness Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.