Sanxinyuan USB Plug-In Green Beverage Warmers - 3 Temperature Settings, Automatic Shut-off

"The coffee warmer I purchased while still working finally gave up the ghost. I'd purchased it in the 90"s for my desk while working and continued using it after retirement after I'd injured my back working in the yard so was confined. Ordered this unit and anxiously waited for delivery. Found out it was intended for USB port, not simply plug into wall outlet. Had to go purchase an adapter ($10.95) finally got it plugged in a day after receiving. Put a hot cup of coffee on it, took a sip maybe 15 minutes later and had moderately warm coffee. Few minutes later another, colder yet. It finally cooled down to what I'd say was cooler than luke warm (ugh). Checked all the connections, reread the instructions, put it on hi (75c), got another cup of coffee, same test, same result. Unplugged from the adapter and plugged into the computer USB port, put a cup of hot water on it which was cooler than luke warm in 30 mins. Just does not heat. The plate is a little too warm for comfort to put you hand on but might take a few minutes to raise a blister. Am so disappointed and now looking for something else after returning this one. My opinion is a complete waste of money. Don't pay attention to the original price of $50 something dollars on sale for $14 something dollars. It is not a bargain!!!

It turns on and gets warm. But the heat doesn't transfer to the cup. Cold coffee in 10 minutes. It is usb powered which was not clearly advertised. The temperature display is in C° with no way to switch it to F°.