Backpack of Sharing

The markings on this backpack are unreadable, but the workmanship is clearly that of a master craftsman

This backpack has similar functionality to a handy haversack with a central pouch (80lbs/8 cubic ft) and 2 side pouches (20lbs of material/2 cubic ft), each of which is an extradimensional space. However, this backpack comes with 1d4 +3 fanny packs (Fanny Pack of Sharing). If you wear a fanny pack, you can access the backpack through it. This counts as a free action.

The backpack needs to be within 300ft and can't be accessed directly when a fanny pack is being used, and vice versa.