I got a 19 from 21a recently and the SA gave me a QR code to scan and we registered the bag at the store. I only had to put my name and serial code in. Then the next day I received an email with a link which shows me a pic of the bag, the serial number, material, model, date of purchase and expiration date of the warranty size etc. It‘s a pretty solid way to authenticate bags tbh, given that resellers would provide the link etc, definitely makes it harder for resellers to resell and prove authenticity though, but safer than card imho