If two cereal boxes are randomly selected from the shelf to purchase, what is the probability that both of them have the secret decoder ring?

Inside the box of every cereal box contains a surprise gift. The store manager assures employees that 11 of the 51 boxes on the shelf have a secret decoder ring and inside the other 40 boxes on the shelf contain a different gift. If two cereal boxes are randomly selected from the shelf to purchase, what is the probability that both of them have the secret decoder ring?