- preg_match_all: documentation ( source)
<?php
$value = "4.3";
$string = "4.2 MM - 4.4MM (30PTS)";
preg_match_all("/([0-9.]+)\s*MM/", $string, $matches);
// var_dump($matches[1][0], $matches[1][1]);
if($value>=$matches[1][0] && $value<=$matches[1][1])
{
echo "Yes in range.";
}