Bests & Worsts Reviews from Amazon

In all cases I preheated them with boiling water and left the boiling water in the unit for 5 minutes before refilling with my hot beverage. This is a must or you loose a lot of heat immediately when you fill. So always pre-heat! We used these for an outdoor winter party and it was a great est. The day of the party it ended up being 15F and windy. They were on a table somewhat protected from the wind but even the last drinks four hours after filling were still too warm to immediately drink. I also did a test, I filled them with boiling water (after pre-heating) and immediately checked the temp with a meat thermometer. It was 185F. I then placed them outside for 24 hours with outdoor temps ranging from 20F to 28F. After 24 hours the water still measured at 112F. I cannot complain and am very happy we bought the durable all metal style.