The incredible chartres board [1]

This is a very easy thing to check your awaken state double brain frequencys, take a look for the symbols till a third one in the middle appears. In every blink of an eye you see the left or right colors in the middle column too. With both eyes you should see solid purple, the quality of the solid color shows the shifting frequency of the brain sides. Works best when this was printed on a full page. Get better with training, gives pretty dream effects when used before sleeping.