Series 4 of the Treasure Book was released on July 31, 2009. It could have been accessed by entering a single-use unique code from real-life series 4 merchandise into the Unlock Items Online page. Each code entered allowed the player to select any two clothing items from this series of the Treasure Book to redeem for their account. Any color of puffle up to white could be adopted as well (if the player did not already own the maximum amount of puffles), and adopting a puffle counted as one item.
The clothing items redeemed from the Treasure Book were all their "unlockable" versions (signified on their icon with an opened padlock inside a blue circle), and these versions could be freely worn even without membership. Any color of puffle adopted could be interacted with and walked without membership was well.
On October 4, 2011, series 1 through 13 of the Treasure Book were removed. Since then, if any applicable code was entered into Unlock Items Online, only the most recent series of the Treasure Book was accessed.
Items in the tables that are marked with green backgrounds are items that were first released in this series. This only applies to items that are completely new, not previously existing items with new unlockable versions.
