A finishing rub is a very fine powder packed with a lot of punch. Its used to add just a little zing to the meat just before the box gets closed up. It is not the same rub that you use during pre-cook. Some good ones are Happy Ending by Big Poppa Smokers and Smoking Guns Gun Powder. Its applied on top of the sauce, and if need be, a quick spritz of apple juice will help it melt into the sauce. When used correctly, it can definitely add that lats little layer of flavor that can set your box apart from the rest. I would recommend getting a couple and then try it on a practice cook before using it at a comp. They are pretty cheap and come in small shaker bottles. They can be used on any entry, but I think the most common is ribs and chicken.