C# get hard disk serial number

            //创建ManagementObjectSearcher对象
            ManagementObjectSearcher searcher = new ManagementObjectSearcher("SELECT * FROM Win32_PhysicalMedia");
            String strHardDiskID = null ; // Store the disk serial number
             // Call the Get method of the ManagementObjectSearcher class to get the hard disk serial number 
            foreach (ManagementObject mo in searcher.Get())
            {
                strHardDiskID = mo[ " SerialNumber " ].ToString().Trim(); // Record the obtained disk serial number 
                break ;
            }
            label1.Text = " Hard disk serial number: " +strHardDiskID; // Display the hard disk serial number