Backpack

are items that expand a player's carrying capacity.

Use
Backpacks have 9 Docks, so they are able to carry up to 9 different Items. However, attaching the to the player's back uses a Dock, so a  effectively increases carrying capacity by 8 Docks. The can be attached by grabbing it and reaching behind the Player's back, then letting go of it. The can be retrieved from the Player's back by placing their hand behind their back and grabbing it.

Obtaining
can be obtained in a number of ways:
 * Several Backpacks are scattered across the Overworld when a new server is started
 * In the Town Hall, it is possible to sacrifice ten Wood, ten Stone and five Copper Ingots