ZENDO Perfect Temperature Smart Mug. Cools Coffee Instantly To Drinking Temperature. Vacuum Sealed Copper Insulated Travel Tumbler. (Black)

My absolute favorite mug. It takes tea made with scalding water and within minutes brings it down to the exact perfect temperature that I like, as opposed to the burning level that most people seem to tolerate. No more burned tongue hurting for days! Even after half a day the tea is still enjoyably warm. I want three more like it! But they seem to be out of stock :/

Pretty much works as advertised. Rapidly cools hot beverages to a drinkable temperature and keeps it there for hours. I wish the temperature that the drinks settle at were a just little hotter and that it held more than 10 oz (300ml).

The temperature control absolutely works! My only complaint is that it drips from the rim, I think coffee gets up on the lid then it drips when drinking. Other than that it’s a very cool cup.

This is exactly what I needed. It cools as well as adding an ice cube, but doesn’t water down the drink. I fill up with coffee at the cafe, walk 200 feet to my office giving a gentile shake, and it is cool enough to drink as I sit down. It will then keep the coffee at a drinkable warmth for quite a while.

The quality is very nice, a little heavy but feels very sturdy. The lid is a screw-on, no leaking issue. The design is very elegant, same size as a 20 oz smartwater bottle. It really cool hot water down to drinkable temperature very quickly. I use this to cool boiling water down to lukewarm before feeding my child. No more waiting or testing it on my skin anymore!

I'll nurse a cup of coffee for hours, and this mug keeps it evenly warm for hours. Before I found this gem I'd only enjoy the first few draws before my coffee got cold. If I could suggest anything to make this product better, it would be to keep more heat in the liquid so it doesn't cool down as much.

Very occasionally, at random, this thing does an amazing job at turning scolding coffee into something drinkable within minutes. Most of the time however, it is just as hot as when I pour it in, usually for most of the day

For a $40 coffee thermos, I had high hopes, but was unfortunately left disappointed.You must leave ~4 inches of space at the top of the mug, otherwise the lid will cause the liquid to overflow. Unfortunately there is no fill marker or warning, so you do not discover this until there is coffee all over you. Additionally, the lid is of terrible design. Anytime I remove the lid, the liquid is trapped in the crevasses of the lid and essentially spills all over each time it is removed.