From the Kickstarter:
"If you want an alternate way to explore the dungeon, or perhaps just a great way to store your cubes in luxurious style, you should enjoy this beautiful custom printed cloth bag. The bag measures 5x7 inches and you can even fit the entire game inside the bag for ultra portability!"
This double-pull drawstring features the Dungeon Drop image on one side and blank, gray velvet-like material on the back.
For more information, please refer to the BGG listing for Cloth Bag of Holding.