One problem I have not seen addressed yet, is the fact that there is no way to keep track of the flavors of my cartridges. I have at least 4-5 cartridges, with different flavors in each, but no way of keeping track of which is which. I have not yet figured out a good way of labeling them. The only thing I have came up with, is that I could use a marker, and mark the small white cap that comes with each cart. Has anyone come up with a good way of distinguishing the flavor of each of their carts?