Checking on the unit label of NSB-25
You can find the 11 digit serial number below the barcode in the lower left corner of the main unit. The serial number begins with “NSB”.
(ex : NSB25XXXXXXXXX) (NSB-25+ )
 Using the setup menu
If your product does not have its serial number printed on the main unit, you can find it in the [Setup] menu.
Select “Setup” icon in “XCopy/MCopy Ready”.
Find the serial number on the “Firmware Update” line.