$re = '/^\["[PM]\d{3,5}Z[pm]\d{3,5}(?:","[PM]\d{3,5}Z[pm]\d{3,5}){7}"]$/';
$str = '["P4950Zp550","P4950Zp575","P4950Zp600","P5000Zp550","P5000Zp575","P5000Zp600","P4975Zp550","P4975Zp600"]';
preg_match_all($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