The second Dwig series I started to collect, which has been complete for quite awhile, is the Reverse Mirror Series. In all the cards, a girl is holding a postcard up to a mirror and the writing inside the mirror is backwards. In order to read the message, you are supposed to hold the card up to a mirror. The message on the bottom of the postcard instructs the recipient to do so.
The series is published by Charles Rose and is series number 30. There are a total of 12 cards, all with either a purple, red, or turquoise border.