The info in the LUNx strings is used to display the device name in Device Manager and the Properties windows. The format for the string is xxxxxxxxyyyyyyyyyyyyyyyy, where x is the manufacturer, and y is the device. Windows will automatically place a space between the x and y boundary. If the x spaces are not all used, then they should be left blank and Windows will truncate them.
For example, a LUNx string of "12345678ABCDEFGHIJKLMNOP" would show up in Device Manager as "12345678 ABCDEFGHIJKLMNOP".
Likewise, a string of "1234 ABCDE" (note spaces to fill remaining x slots) would show up as "1234 ABCDE".
Note that "1234 ABCDE" would appear as "1234 ABC DE" in Device Manager.