a guide is employed on air conveyors of the type that suspend conveyed objects from an intermediate enlargement , for example , conveying plastic bottles by suspending the bottles from their neck rings , where the guide limits the upward movement of the bottles conveyed by a conveyor system preventing the bottles from becoming wedged in the air conveyor and jamming the flow of bottles through the air conveyor while permitting each of the bottles conveyed to swing freely forwardly and rearwardly from their neck rings as the bottles are conveyed through the conveyor .