document.observe('dom:loaded', function(){
		$('banner_CNG_1').hide();
		new PeriodicalExecuter(morphBannerCNG, 4);
	});

function morphBannerCNG(){
	if($('banner_CNG_1').visible()){
		var visible = 1;
		var hidden = 2;
	} else {
		var visible = 2;
		var hidden = 1;
	}
	$('banner_CNG_'+visible).fade();
	$('banner_CNG_'+hidden).appear();
}