Lexar began shipping their 80X line of cards in late June 2004. The first edition of 80X line cards only got a write speed of about 6.8MB/sec. In Oct 2004, Lexar began to ship a revised version of their 80X cards, which is known as the second edition with improved write speed of about 9.7MB/sec.
As of Jan 2005, second edition cards remain identical in appearance to their first edition predecessors and are sold in similar retail packaging. A red mylar tab sealing the end flap is the one hint that a second edition card lurks inside or the last four digits of the edge stamp, visible only once the package is opened, also differentiate first edition from second edition. If the last 4 digits is A4B6, its a second editon 80X card with improved write speed.
Correct me if i m wrong.
the second edition is supposed to have a red round seal sticker on the openings of the package as what mpenza and shawnlim have mentioned.
best way is still to check the edge stamp.
ask the retailer if the card is a second edition. if he says yes, ask him to open the box and check the edge stamp for confirmation. if he doesn't want to open the box, ask him if you could return it should the card be a first edition. if he's confident of his product he will show you. if not, it's your call to take the risk.