Stress Card with stock design on thicker .030 over-laminated for durability and higher perceived value! Excellent event hand out! Although the Stress Card with a liquid crystal tab is a promotional product, there is validity to it. This was designed by Dr. Alfred Barrios, a clinical psychologist in the early 1980s and designed to be used at room temperature (70 – 74 degrees) and by people who do not have circulatory issues. The crystal is set to activate to different levels (colors) at specific temperatures. The crystal measures the body temperature. When relaxed, the blood vessels are at the extremities (fingertips, nose and toes), which makes those areas warmer. When anxious or stress, the blood vessels move inward, making those areas cooler. It should be emphasized from the start that the Stress Card is not just a stress test. It is also a stress control device. What color you register initially is not as significant as the fact that you can change the color by going through one of the highly effective quick relaxation techniques on the back of the card. Not only is this card used in the Health Care Industry, but it's also been used to teach Biofeedback to pilot training FAA training, Navy and Airforce, Alcohol and Drug Rehabilitation, Mental Health, Cigarette Smoking Rehabilitation, etc.