Review on 🥃 Premium Double Wall Glass Cups - 8.5oz: For Ultimate Temperature Control and Elegant Sipping Experience by Randy Holt

In order to prevent the hollow part of the cup from being pressurized, there is a vent hole at the bottom of the cup. When washing the cup, water enters the vent and does not drain. Most of the water squirts out when you pour hot coffee into a cup, and the expanding air pushes out most of the water, but there always remains a layer of sloshing water. between two walls. Also, these cups (necessarily) have very thin walls. My inner wall broke from stirring with a teaspoon. It really does keep your coffee warm for a lot longer, which is why I keep buying and throwing them away. . I wish there was a better option.