Hi @mir.a ! Looking at the Design from the Original Link, it seems that the Ember functions mainly between lukewarm and scalding temperatures to bring your beverage to the perfect drinking temperature which can be set by you. This probably means that when you beverage is cold, the Ember can heat it up internally to your desired temperature and maintain it there. The converse is true too. When your drink is scalding hot, the Ember can cool it down till the perfect temperature for drinking and hold it there too. By seeming to function within this range of warmer temperatures, I don't think the Ember can keep cold drinks cold like the Yecup. That seems to be something only the Yecup has at the moment. The ability to hold drinks at low and high temperatures. Hope this helps!