This tent sits on the left side of the Sear Zone stationary chamber. It rests on a ledge that is welded to the inside of the grill barrel. Its function is to shield the auger feed assembly so that grease will not drip into the moving parts.
In the manual for the Oklahoma Joe’s Rider DLX Pellet Grill 900 and 1200 models this is listed in the parts key as item #62