This View-Master viewer was only available as part of a Harry Potter question and answer game. The right side of the card holds the question; the left side holds the answer, which can be viewed by looking at it through the decoding card. The decoder appears to be a lenticular screen—see the demonstration in this YouTube video at 4:35.

There were 60 cards total. A set came with 5 random cards and the decoder card. There was also a collector's case. The viewer could be purchased with a single card, which is how this one came (Silvester 2021).