GrillGrates(TM) amplify heat, prevent flareups, make flipping foods easier, keep small foods from committing suicide, kill hotspots, are easier to clean, flip over to make a fine griddle, and can be easily removed and moved from one grill to another. You can even throw wood chips, pellets, or sawdust between the rails and deliver a quick burst of smoke to whatever is above. Every gas grill needs them.
***Update 2...Now over a year in. I have easily fired this beauty up at least 150 times...yes, 2-3 times a week. With the cover, the care, and occasional, deep clean (just deep cleaned it for the 4th time..about a 1-2 hour simple process) it honestly looks like it did the day I set it up and works just as well. My pizza is the talk of my son's youth group buddies (don't want to tell them its Wal-Mart take and bake) and I can now cook/smoke/grill literally anything on this pit. My biggest problem now, if you read below about not using my 4K Cal Flame gas grill anymore (STILL haven't since), is that my wife if busting my chops to tear out my original 'outdoor kitchen' to free up more space on the patio! I'll keep making excuses to avoid that, but truth be told, this pit rendered my Cal Flame useless. Not one complaint...don't hesitate to buy this pit (remembering the $400 target price).***