Progress Device
A Save Device is an item that can be used in Pokemon Super Mystery Dungeon.
It allows the player to set up a "save spot" in a dungeon. It will allow the player to save progress in a dungeon. This way, if the player is defeated and they select to restart from their save file, it will restart where the player last put a Save Device down. It will not reappear if one returns to the dungeon on a separate expedition.
A Save Device + behaves as mentioned above, but it also allows the player to quit the dungeon if defeated without the loss of items and/or Poke Money.