Provides a quality product at a very affordable price. Packaging and shipping are incredible, too - custom designed for the ink and explicitly labeled. They understand the value of building long-term customer relationships - even with small businesses such as ours - which keeps us coming back every time. Other companies would do well to model Professor Color. No need to look or shop anywhere else. (Full disclosure: We have no personal or financial interest in Professor Color that would bias our stated opinions. We just recognize an incredibly well-run enterprise when we encounter it.)