The mod introduces multiple kinds of bags and an item to turn any item into a bag.

Bags:

• Belt bag
• Small modern bag
• Small backpack
• Modern backpack

Quantum Expanders:

• Quantum space expander
• Advanced quantum space expander
• Turbo advanced quantum space expander

To turn any item into a bag you need to use (right-click) “Quantum space expander”, “Advanced quantum space expander” or “Turbo advanced quantum space expander” while having the desired item in offhand.