A tumbler should not only be more stable (meaning less likely to tip over) than a standard mug or drinking glass, but it should also be more durable. After all, when you're on the go, it's inevitable that you're going to drop whatever you're drinking and glass is NOT known for its durability. On top of that, a good tumbler should also have a lid so that, even if you do knock it over or drop it, you don't have to worry about your drink spilling across a desk, table, or floor.
glass is 4 times thicker than regular glass mugs giving you more hot or cold drink
