FBA uses Amazon barcodes (FNSKU) to identify and track inventory throughout the fulfillment process. Each item you send to an Amazon fulfillment center requires this barcode.
Amazon barcodes must be applied to all products you send to Amazon warehouse including.
You can print Amazon barcodes and apply them to your products yourself, or Amazon can print and apply them for a per-item fee. For more information, see Use an Amazon barcode to track inventory .