By adding 18 to 24 inches to the tank height, a Powered Fold-Out Grain Tank Extension can increase a combine's carrying capacity by as much as 200 bushels, which means significantly more harvesting before having to unload. Custom-made for many combine makes and models, most extensions consist of four rectangular steel side panels that bolt to the machine's sub-frame via hinges that allow each to fold up/down in sequence. They're powered from the cab by a battery-driven electric winch that control four cables (one per panel). Attached to and running between the panels is fabric or rubberized material that, when the panels are opened, create an inverted "tent" that holds the additional grain.