public static function getLeadTimeFactor(string $strFactor, int $iLeadTime)
    {
        // minutes
        if ($iLeadTime < 60 || $iLeadTime % 60 !== 0) {
            $iNum = $iLeadTime;
            $iUnit = 1;
        // hours
        } elseif ($iLeadTime % (24 * 60) !== 0) {
            $iNum = $iLeadTime / 60;
            $iUnit = 60;
        // days
        } else {
            $iNum = $iLeadTime / (24 * 60);
            $iUnit = 24 * 60;
        }

        return ${'i' . ucfirst(strtolower(str_replace('lead_time_', '', $strFactor)))};
    }