If you sell products online that have a standard UPC barcode associated with them, then list that barcode on your website alongside the manufacturer’s part number (and description) next to each product.
People sometimes search using a search engine for manufacturer’s part number if they are looking for a specific product – if you don’t list it you can’t be found for that search.
But why barcodes? Well it’s pretty rare for somebody to type in and search for a barcode… unless they are using a modern smart phone shopping app. These take a photo of a barcode, analyse it and then search the web for it.
If you don’t list it, you can’t be found for it!
And while you’re busy sorting these out, make sure that you put these details into your Google Merchant Center data (you do have your products listed in Merchant Center, don’t you?) – the more data you have in Merchant Center, the more likely you are to appear in the search results.