public function checkStockLevel($qty)
    {
        $stock_param = $this->config()->get("stock_param");
        $item = $this->Match();
        $stock = ($item->$stock_param) ? $item->$stock_param : 0;
        $return = $stock - $qty;

        $this->extend("updateCheckStockLevel", $return);
        
        return $return;
    }