NRDC : Global Warming - Heat Sensitive Mug
information
The external surface of the cup is printed with a second layer of heat sensitive ink that is revealed when hot water is poured into the cup.
credits
Via www.nrdc.org/
The external surface of the cup is printed with a second layer of heat sensitive ink that is revealed when hot water is poured into the cup.
Via www.nrdc.org/
