These Heat Sensitive Hypercolors really make their mark! Hypercolor Thinking Putty is thermochromic -- just a touch from your hands or a warm coffee mug will reveal a new "hot" color. Allow it to cool off or stick it in the fridge! Then the "cool" color will be restored. Made in the USA! Invisible in the jungle but sure to stand out in your hands, Chameleon Thinking Putty's lush, tropical green explodes into a bright fluorescent yellow with just a touch of heat. And, unlike the real thing, all this Chameleon needs is a daily squeezing!