Remember Mood rings? Sure you do, thermal sensitive papers that change color with heat are a neat novelty but Nike has managed to find a way to cover kicks with that same technology. Unlike chromatech by adidas, the Heat Map Pack uses surface heat to shift colors. Nike has covered the Air Max 90 and Uptempo Heat Map in that thermal sensitive material. A pair of kicks outside in a sunny day will get brighter so you can rock the same pair of kicks as someone else and have them look completely different.