I used the two grates from the firebox, on the Oklahoma Joe Highland, and covered them with very large heavy duty foil trays to create the tuning plates. One is angled across the cooking chamber covering the firebox hole, the second grate is covered exactly the same way and sits just in front of the first. This forces the heat under and along the cooking chamber which has resulted in just a 5 degree temperature difference along the entire cooking chamber! I have not found the need to run tuning plates along the entire length of the cooking chamber and when I did try, it never made any significant difference? I use the OJH exclusively for smoking so had no use for all the grates that came with it. It does work well and saves a ton of cash on plates! Not suggesting anybody should do as I have, just saying.?