I bought this product a month ago, and to begin with I was pleased that I had a working authenticator. But now, I just went to log onto World of Warcraft and type in my authenticator number, but nothing popped up on the screen. It's attached to my keys, which are in my school bag a lot of the time, but there's no damage at all on the outside. Unfortunately authenticators are not battery replaceable which isn't helpful at all. I now plan on buying an authenticator from the Blizzard site, hoping that maybe it might work this time. I'm just not very impressed by how little this product has lasted me considering that it costed me £10.
Just an update! Because I keep getting replies to this comment, you don't need to reply to me anymore!! I got a new Authenticator from the Battle.net website ages ago! And it works fine!