I have the grease dispenser as well, a large and small.

Here is the small one that I have. I guess it is .9 liters

Here is the large one. It is in the bottom left corner of the picture.

I generally use the large one with groups for hot water. It pours nicely and holds about 2 liters (I think).

The thing about the mug is that it is smaller, weighs less, and is cheaper than the small grease pot. Both diameters are the same, but the .9L grease pot is taller. Anyways, it is another option. To each his own.

Oh, and I like to give the mug away as prizes to my scouts (among other small useful things.) Being $2, it doesn't hurt me much, and the boys love getting a useful piece of gear. I also have a few on hand to "lend" for boys who show up with nothing to cook with. It is no big deal if they break or lose it.