Because it's double walled, each wall is thinner than a regular mug, to keep weight down. There is a small plug on the bottom that keeps moisture from going between the glass layers. The insulation works very well.

These are great and work well and look great but the glass does feel kind thin. They are def different from 'the other brand' they match any decor due to being clear. Look nice and seem durable.

A visual treat and sure to impress your guests. We use these for yogurt parfaits,cappuccinos, and wine in our rv. They fit easily into my medium sized hands.

Very good to hold the coldness of your drink. Remember to hand wash and keep it out of the dishwasher. Sometimes when making certain teas you have to have the water boiling hot.

Some of them have tiny halls in their outer glass, so whenever you put them in the dishwasher, water will leek in and get stuck in between the lairs, with no way to get out.