The USB mass storage specification requires that all USB mass storage device has a serial number unique for that VID/PID combination except for mass storage devices that implement USB mass storage CBI protocol. Cypress offers free manufacturing software tools that will assign a unique serial number to each device which is programmed using the tool. These manufacturing tools are included in the development or reference design kit files. Please note that Cypress only allows the use of its VID for mass storage development. Products sold to end users must use your own VID. Please contact the USB-IF for more information on obtaining a VID.