Maxi-Cards are the size of a normal picture post card. (a quarter of an A4 sheet of paper)

They are issued for the first day of issue for a stamp and ususally depict the same topic as the stamp - in this case the same lighthouse.

We got these via a contact we have in China. I am not sure where in China you can buy them.
They are available at Delcampe Auctions ... here:
2006 China(Chine) Maximum Cards---Lighthouses(4v), lighthouse phare leuchtturm theme!!

(Actually the seller is the guy who supplied us!)