3 x 19.5" x 8" Big Blues with a 10" x 2.5" pre-filter housing containing a 5 micron pre-filter. 
Various options available with carbons.
You could use Catalylic carbon if your tap water contains Chloramine, Or if you have Chloramine and metals use a mix of Catalytic carbon and Bone Char, or Chlorine and metals use GAC and Bone Char or just Bone Char. The combination of the small big blues also comes with fittings of your choice.
Great choice if you are stuck for head hight to install the taller Big Blues.
If you are not sure what you need please call us and we will be ble to advise you.