Backpack of Sharing

The markings on this leather backback are unreadable, but the workmanship is clearly that of a master craftman. The bag has two front pockets and two side pockets, strapped to the main pocket.

Everyone wearing one of the removable pockets can access the backpack through it as a free action. However, the main backpack needs to be within 300 feet and the backpack can't be accessed directly when a removable pocket is being used (and vice versa).