From my understanding they are the same as the Aero I skirts. They superseded the original Aero I skirts to this number. The G2X means they come unpainted in primer gray.
In my opinion the Aero I skirts look better too. I personally don't like side skirts that have a "twist" to them, which the Aero II skirts have. Porsche also designed the Aero I skirts to not catch your leg when getting out of the car.
Aero II skirts
[IMG]http://www.****************************************************.com/mm5/graphics/00000001/986%20with%20sides4.jpg[/IMG]
The number for Aero II skirts are 98655998302 and 98655998402