Notations in M letter sizes ranging from 20M to 1.6M for testing at various distances. Each page it’s own contrast level at 100%, 2.5% and 1.25%. This flip book is great for vision studies and research world wide. The Tumbling “E” vision chart uses only one optotype for testing. Patients not familiar with the Roman alphabet simply have to gesture or sign which direction they see the “E” facing. This is a helpful test for patients that are illiterate or mute, also. This Tumbling “E” flip book contains three contrast levels for accurate sensitivity screening.