$re = '/\w+_\d+_\w+_(\d+)m_Length_(([0-9]*[.])?[0-9]+)_Width/m';
$str = 'Footballfield_01_CampNou_108m_Length_68.5_Width
Footballfield_02_Bernabeau_105m_Length_68.5_Width';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php