public static function create($formattedString, $offset = null)
    {
        if (strpos($formattedString, '/')) {
            $dual = new VF_Wheel_BoltPattern_Dual($formattedString);
            return $dual->getPatterns();
        } else {
            return new VF_Wheel_BoltPattern_Single($formattedString, $offset);
        }
    }