Joe Lee 3 This is the first of such kind of device I used, here is my finding during use.I test it indoor without air conditioning, with temperature of 30°C and relative humidity of 70%. I used water bath method to cool the bottle, it took an hour to cool to 18°C, and then slowly cools down to 14°C in the 6th hour. When indoor temperature 25°C and lid closed it can cools down to around 8°C in an hour, that’s about the best it can do in the given condition, where on the hot side it heated up to 60°C in 5min.I found the device shown random no. when power on, and lacking a real time temperature display is a negative, after all it is more useful for heating up things, but much less efficient in cooling down.