Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Best coffee mug ever, a thermos, duh?

Tried a few mugs out there. If you are serious about keeping your hot beverages, hot, and I mean hot, for 4-6 hours, warm through 8, then there is no other mug. Oh yeah, it's spill proof and has flawless pouring for no-spill drinking too. Limp wristers, a caution, if you tighten the lid moderately, the heat creates a suction and the lid tightens even more. This is the way to keep the liquids spill-proof and hot, but you can tighten it less for easier opening.