Review on NG1702 - Mustard USB Cup Mug Warmer Coaster in Dark Brown Hot Cookie by Brad Laverentz

You can't deny that this is the coolest mug warmer out there. I have a very large mug at work and the platen area of this warmer was more than enough for the bottom of my mug. After I had drunk half of the coffee, I put it on the heating pad for an hour; without temperature change. I drank some more and put 1/4 of the coffee on the heating pad but it still didn't heat the coffee. I noticed that my mug has a slightly concave bottom like all the other mugs in the office. None of these mugs worked with this warmer. I place the penny on a hot plate to remove the heat between the plate and the bottom of the mug. However, he neither warmed up the coffee nor the cup. It's a fun product but not hot enough to warm a coffee mug. I still love the design but I feel like I need to find a solution that works and allows this product to be used as intended. Considering that copper coins removed heat from the plate I would suggest finding a copper mug. They are also known as Moscow Mule mugs. It would be sad not to use this fun piece of art.