Backpacks are equipment items used to store blocks, including ores. They are purchased at the shops in every zone.
Storage is the sole attribute of backpacks, and indicates how many blocks the backpack is able to carry before the contents must be sold for Coins to empty it. The only exception to this rule is the Quantum Backpack, which allows players to decide when they want to sell their contents rather than being forced to after amassing a certain amount.
Unlike other backpacks, these are purchased with Rebirth Tokens instead of Coins and the shop itself can be accessed at any vendor. Rebirth Shop backpacks are permanently unlocked once purchased, not lost after the user Rebirths.