Phantom Pack

You gain access to a magical pack that is only accessible by you. To reveal and open the pack, you put two fingers next to each other in the air, pointing down, and pull them in opposite directions as if you were opening a bag. The opening to the pack is a circle revealing the pack inside of it, the diameter depending on how far you pull. The pack can hold any amount of items of any size. If the carried weight is to exceed 50 lbs, everything stored in the phantom pack gets dumped on the ground in front of where you are standing and you cannot reopen it for a week.

This pack cannot be opened by other creatures, but other creatures can access the space inside if it is. It essentially acts as a better backpack, as it doesn't inflict weight on you or can be opened by others.