How do they work? Their Kickstarter page says:
his material is designed to melt at 140 degrees Fahrenheit, and absorbs a lot of energy as it melts. This is how Joulies cool your coffee down three times faster than normal. Once it reaches this temperature, the special material begins to solidify again, releasing the energy it stored when it melted. This is how Joulies keep your coffee warm twice as long.I'm pretty sure I'll be getting one of these for Father's Day. I'll let you know how awesome they are then.