 Sure. To give you an example, we have to get into the weeds just a tiny bit. So the mail that comes to your house falls into one of two broad categories. It's either preferential mail or non-preferential mail. Preferential would be like first class mail, the letter that you send to grandma, your bills, things like that. Non-preferential is like standard mail, non-profit mail, things like catalogs, solicitations, stuff like that.