Like Zilla and SG said, they are less effective on smaller pits. You will see a small difference but on a small pit the costs far outweighs the benefit unless you manage to do it yourself and then again, you won't see much difference in the hot spot. In fact, you will more than likely move your hotspot and once the tuning plate gets hot and starts radiating heat, you now have a larger hot spot. Tuning plates work best in minimum 20" diameter pit that are at least 48 inches long on the food chamber. Not to say that a 20" in a shorter lenght won't benefit from tuning plates, but you really start noticing the "even" effect on longer and larger diameter pits.