/**
  * Set request variable name which is used for apply filter
  *
  * @param   string $varName
  * @return  Mage_Catalog_Model_Layer_Filter_Abstract
  */
 public function setRequestVar($varName)
 {
     if (Mage::helper('catalin_seo')->isEnabled()) {
         $attrUrlKeyModel = Mage::getResourceModel('catalin_seo/attribute_urlkey');
         $varName = $attrUrlKeyModel->getUrlKey($varName);
     }
     return parent::setRequestVar($varName);
 }