Database Call from custom html module

Long story short, I am severely editing the product display page. I need to call upon the description (or else a custom field that is a replica of the description) in a custom html module on the same page.

These gives me the following error:
<?php echo $this->row->product_centers_description; ?>

or

<?php echo $this->element->product_description)); ?>

ERROR: Fatal error: Using $this when not in object context in....

However, I can call upon it individually as shown below without errors, though that won't work because I can't make a new custom html for every single product page:

<?php $class = hikashop_get('class.product');
$prod = $class->get(2);
echo $prod->product_centers_description; ?>

Please help,
G

Can you show me, using the bottom code as a rough draft, how to call on "product_centers_description" using the ID directly from the URL? I really appreciate how excellent the customer service is around here. Thank you.

Let me simplify:

I need this code...

<?php $class = hikashop_get('class.product');
$prod = $class->get(1);
echo $prod->product_centers_description; ?>

To pull the "get(id)" from the url or some other way than "$this", because $this gives me errors:

retreatwell.com/index.php?option=com_hik...yout=show&Itemid=274

So combing the two would look something like this:

$product_id = (int)hikashop_getCID('product_id');
if(empty($product_id)) {
	$menus	= $app->getMenu();
	$menu	= $menus->getActive();
	if(empty($menu)){
		global $Itemid;
		if(!empty($Itemid)){
			$menus->setActive($Itemid);
			$menu = $menus->getItem($Itemid);
		}
	}
	if (is_object( $menu )) {
		jimport('joomla.html.parameter');
		$category_params = new HikaParameter( $menu->params );
		$product_id = $category_params->get('product_id');
	}
}

$productClass = hikashop_get('class.product');
$prod = $productClass->get($product_id);
echo $prod->product_centers_description;

Awesome!