After creating the basic product as listed here. You will select the attribute serial controlled. If your product always arrives with the same sequence for the serial number, you can add a serial number mask to prevent accidently scanning the wrong barcode into the serial number field. In the photo below the mask is DJ plus five digits. Unknown digits are notated with an underscore _.
Example: DJ_____
P4 Warehouse Serial Number Setup
Attribute settings need to be selected priory to transacting any transactions for this product in the system.