function setCheckedValue(radioObj, newValue) {
	if(!radioObj)
		return;
	var radioLength = radioObj.length;
	if(radioLength == undefined) {
		radioObj.checked = (radioObj.value == newValue.toString());
		return;
	}
	for(var i = 0; i < radioLength; i++) {
		radioObj[i].checked = false;
		if(radioObj[i].value == newValue.toString()) {
			radioObj[i].checked = true;
		}
	}
}

function changeMat(to) {
	var where = to;
	setCheckedValue(document.forms['cart_quantity'].elements['id[1]'], where);
	document.images['mat_TL'].src = 'images/attributes/mat'+to+'_TL.gif';
	document.images['mat_TR'].src = 'images/attributes/mat'+to+'_TR.gif';
	document.images['mat_BL'].src = 'images/attributes/mat'+to+'_BL.gif';
	document.images['mat_BR'].src = 'images/attributes/mat'+to+'_BR.gif';
	document.getElementById('matBG_T').style.background = 'url(images/attributes/mat'+to+'_T.gif)';
	document.getElementById('matBG_L').style.background = 'url(images/attributes/mat'+to+'_L.gif)';
	document.getElementById('matBG_R').style.background = 'url(images/attributes/mat'+to+'_R.gif)';
	document.getElementById('matBG_B').style.background = 'url(images/attributes/mat'+to+'_B.gif)';
}