$re = '/(?<=partNumber=)[\w-]+|(?<=/)\d+$/m';
$str = 'https://www.opsm.com.au/ProductDisplay?urlRequestType=Base&catalogId=12601&categoryId=3074457345616695670&seoNameToken=air-optix-colors-2pk&langId=-1&manufacturer=AIR+OPTIX&facetTokenValue=facet-lifecycle%3DMONTHLY&partNumber=ac-airoptix-colors-2&storeId=10151
https://www.opsm.com.au/womens-sunglasses/ov5514su-kasdan/827934482050';
preg_match_all($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