This add-on pack includes the custom balls:

Glo-Ball 1
Glo-Ball 2
Glo-Ball 3
Glo-Ball 4
Glo-Ball 5
Glo-Ball 6
Glo-Ball 7

Once unlocked and selected, Custom Balls can be used on any table. To change your pinball to be a Custom Ball, select Extras from within the Options of any Table Menu.

More details on the official game page of Glo-Ball Pack ...