This trait can be applied to any object with an interior space or holding area, like a bag, backpack or vehicle interior. In effect, the interior of the item is a pocket dimension of greater size than is possible for the actual volume of the object, allowing one to store vastly larger items inside, assuming they can fit through the opening.

As a Minor Good Trait the item has an interior roughly 10 times its apparent volume.

As a Major Good Trait, the object holds roughly 30 times its apparent volume. Weight is still a factor in both cases, so even if you can fit a hundred gold bars into your ‘magic bag’ you still have to be able to lift it.

As a Special Good Trait, the item has 30 times capacity and its weight is negligible. This counts as two Major Traits.

All TARDISes are assumed to have the Special version of this trait by design (even if not specified in their profile), but their interior space is infinite and the exterior is as weightless as the operator chooses.