Sack of Sacks

The Sack of Sacks is a SkyBlock Menu Upgrade located at the bottom right of the menu once unlocked at which is used to store Sacks.

Obtaining
Like the Accessory Bag, the storage capacity increases as players progress in their Collection.

Increasing Size
The size of the Sack of Sacks can be also increased by upgrading it in the Account & Profile Upgrades section of Elizabeth's menu. Each upgrade adds additional 2 slots to the Sack of Sacks. The costs and upgrade times are following:

Usage
The Sack of Sacks allows players to store different Sacks. With all Sack of Sacks Account & Profile Upgrades, it can contain up to 28 Sacks.

Note that backpacks and Trick or Treat Bags cannot be stored inside.

Trivia

 * One can upgrade the Sack of Sacks with the Account & Profile Upgrades even before obtaining it at all, although it still cannot be used until it is unlocked (a message will appear on the lore of the upgrade item saying that one hasn't unlocked that feature yet).
 * Multiple sacks of the same type can be placed into the Sack of Sacks.