You can see in the header_php.php code for that page that the model number gets appended if it exists:
Code:
if (zen_not_null($review->fields['products_model'])) {
$products_name = $review->fields['products_name'] . '<br /><span class="smallText">[' . $review->fields['products_model'] . ']</span>';
} else {
$products_name = $review->fields['products_name'];
}
You can review this and other variables available inside the header_php.php file, or in the case of other pages, the main_template_vars.php file for the given page. You can add your own if you so desire as well.