Bests & Worsts Reviews from Amazon

I bought this tumbler for my girlfriend. When I got it home; I opened it and poured in water from the teakettle. Using a instant read food thermometer I checked the temp. I started at 206 deg, closed the lid and let it set. at 1 hour the temp was 193 deg. At 2 hours 182 deg; at 4 hours 164 deg; and at 6 hours temp was still 152 degrees. over a 6 hours period the temp only decreased 54 degrees. During my test I noticed that the outside of the cup did not feel at all warm to the touch; the only part that changed at all was the top and then only slightly warmer. I also tested the seal by turning the cup upside down for one of the hours with no leaks at all. I do recommend that you don't put liquid that is too hot in it expecting it to cool down to drinking level on the way to work. you won't get anything to drink.