The Federal Reserve has mixed in new features to make the bill more difficult to replicate, like a blue security ribbon running down the front. When the bill is tilted, columns filled with the number "100" and tiny bells rotate. Tilt left to right and the columns move up and down; tilt up and down, the columns move left to right. The ribbon is woven onto the paper, not printed, making it tougher to duplicate. It's composed of thousands of lenses that magnify the marks and make them appear to move in different directions--not easy for a counterfeiter to remake in a basement.