At times on some electronic devices the serial number can be tricky to find, but icon Pro Audio makes it pretty simple to locate the Serial number.
Generally serial numbers are located on the rear of all units. But, due to a recent change the serial number is now found on the bottom the unit.
The serial number is 10 digits with a bar code and it comes on a white sticker located inside of a rectangle box on the back of the unit here is a sample picture.
Originally being located on the back of the Icon Pro Audio Units the serial number is now located on the bottom, but the serial number still can be located on the back for most units.