public function get($product_class_field_id)
    {
        $result = null;
        $this->hook->attach('product.class.field.get.before', $product_class_field_id, $result, $this);

        if (isset($result)) {
            return $result;
        }

        $sql = 'SELECT * FROM product_class_field WHERE product_class_field_id=?';
        $result = $this->db->fetch($sql, array($product_class_field_id));

        $this->hook->attach('product.class.field.get.after', $result, $this);
        return $result;
    }