This is a great idea and the travel mug is nice. It's a good size and fits in standard auto cup holders. The coffee filter doesn't sit inside the cup however, which is a disappointment since it means that you can't premeasure grounds and leave them in the cup and just add water later when you need it. The grounds need to be measured and carried in a separate container if taking it with for later use. Other than that it works like a travel mug ought to.