My diffuser is the cover to a 30 gallon drum. Drilled full of various sized holes. Sits right on top of the charcoal basket. Works great. Evens out temps, fat still gets to the fire, just not so much. More pros than cons. The one con is more fuel will be used. How much? Well, never did a log comparing the two techniques but I would say about 25% more fuel for a given cook with the diffuser. Just did a 9 hour cook yesterday with a half full charcoal basket, 13" wide x 11" tall, and there was still charcoal covering the bottom. Drum ran perfectly the whole time at right around 220* Here it is.