public function getItemKey($sProductId, $aSel = null, $aPersParam = null, $blBundle = false, $sAdditionalParam = '')
    {
        $aSel = ($aSel != null) ? $aSel : [0 => '0'];

        $sItemKey = md5($sProductId . '|' . serialize($aSel) . '|' . serialize($aPersParam) . '|' . ( int ) $blBundle . '|' . serialize($sAdditionalParam));

        return $sItemKey;
    }