Glowstone Smart Mug 2 : This most resembled an actual mug and was the only mug that was dishwasher-safe. But the design choices felt strange: for some reason, it only worked off the charger, and displayed a bright red light to indicate that coffee was at an ideal drinking temperature, but didn't allow users to control the temperature, nor did it display the temperature. Temperature Hold Test: After charging, we poured eight ounces of hot coffee and set each mug to 135°F (if it could be set), to see how it held temperature off its charging station. Temperature Hold Test, with Liquid Removal: I performed the same test as above, butremoved .5 ounces of liquid every 10 minutes, to represent sips of coffee. Usability of the Mugs: Throughout testing, I looked at the materials each mug was made of and how easy or difficult each was to use. Did the mugs get hot to the touch or were they cool enough to handle?Was the handle comfortable to hold? If it came with a lid, how easy was it to take on and off and/or drink from?

Consistency Tests: I measured each temperature reading of the mug against the temperature it was set to—in general, if the mug was within +/- two degrees, it was considered accurate. I also considered consistency of the temperature over time—did the temperature fluctuate or stay consistent over time? The Ember Travel Mug² measures 7.9 x 3.14 inches and weighs 15.2 ounces, which is slimmer and lighter than the brand’s first-generation travel mug. This change is in part thanks to the new touch-sensitive control panel that replaced the previous manual dial.The Ember Travel Mug’s touchscreen is convenient for those times when you don’t necessarily want to pull out your phone. Price: So expensive Hurkins Smug: The Hurkins performed just fine, but its indicator light was very faint, so I had trouble telling if it was on. The Hurkins only worked on its charger. We tested the second-generation Ember Travel Mug for several weeks, closely examining its performance, ease of use, design, and cost. Keep reading to find out what we thought. Long-Hold Test: I placed each mug on its charging pad, poured eight ounces of hot coffee into each mug, and took temperature readings (using an instant-read thermometer) every half hour for four hours. If the mug offered variable temperature settings, we tested it at 145°F.

OHOM Self-Heating Ceramic Mug: Like the Hurkins, the OHOM didn't have a battery and only worked on the charger. Made of ceramic, this was one of the more attractive mugs I tested and it comes in a range of colors. Most of the mugs came with a travel lid—this one did not, and, despite moving it around to tell the charger it was still in use, it went into “sleep” mode around three hours.