The old Stanley work flask has been the bench-mark of vacuum flasks for good few decades now, and none of the more modern rivals have ever come close to matching its performance. This is basically the up to date version of the work flask, redesigned specifically for outdoor use and it is an excellent bit of kit. I tested mine when it first arrived with boiling water straight from the kettle (after priming) and it was still hot enough to drink 48 hours later, admittedly it was indoors for that time. I also used it on a recent winter trip to Sweden in temperatures down to -28c and it happily served hot drinks all day. A bomb-proof companion with high quality design and construction, highly recommended!