Strange Sack

The Strange Sack is a brown sack from Paper Mario: The Thousand-Year Door. It is found on the 50th floor of the Pit of 100 Trials. The sack increases the number of items Mario can hold from 10 to 20.

Trivia

 * In the Japanese version, when unlocking the blue cage in the Great Tree, the game checks for and removes the Strange Sack from the player's inventory if the player has it (which will permanently prevent it from being obtained again as there is only one in the game). This does not happen in the international versions.