Review on Ultimate Insulated Stainless Steel Tumbler for Camping - DAYMOO by John Holliday

I was amazed at how long my coffee stayed drinkable! Apparently it's a double-walled mug, which I didn't know. This explains why coffee stays hot for so long. Also, in order to drink or close the lid, the sliding "window" in the lid has to be removed, which is quite difficult. Not terrible but just annoying and you have to take it off to clean it. Overall, as I said, this is a great mug, especially as the drink stays hot/warm most of the day.