An order fulfillment system including a frame defining a passageway and a tray positioned in the passageway. The tray is movable between a first extended position wherein the tray is positioned at least partially outside the frame on a first side thereof and a second extended positioned wherein the tray is positioned at least partially outside the frame on a second, opposite side thereof. The tray includes a panel configured to generally block the passageway when the panel is positioned in or adjacent to the passageway. The system further includes a controller configured to selectively allow or block movement of the tray to or from at least one of the first or second extended positions.