$re = '/(?<=Materi.l )\D+/mi';
$str = 'produkt: Tričko, Rozměr 1x1x1cm, Material Aloe Vera 200g A_203
produkt: Tričko, Rozměr 2x3x2cm, Material Aloe 203
produkt: Tričko, Rozměr 2x3cm, Materiál Bavlna 400g N_W245_2017
';
preg_match_all($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