It has always been my understanding that a 12 round magazine was not made prior to the hi-cap ban.  However, I did see about ten 12 round magazines with blue followers for sale at $100 apiece in Orlando the other day.

First, the followers were DARK blue (not light blue, the newest), which indicates either a recent follower conversion, or recent magazine production.

Does anyone else know much about this?

Needless to say, an extra 2 rounds per magazine isn't worth my freedom, so I did not make a purchase.