When fit with this package, the grate temperature on the left side soars past the 650-degree mark and produces those coveted steakhouse quality grill marks, fast cooking times, intense carmelization, color and texture common to cooking over an open fire or gas fired grill. For a YS640, one set of grates (3 interlocking grates) fills out half of the cooking chamber. An extra 3 will finish the set and cover the entire cooking surface. The YS480 pellet grill now comes standard with 3 chrome cooking grates. A set of direct GrillGrates will take the place of TWO of these chrome cooking grates and the 3rd chrome grate will finish out the cooking area.