Hi Pete
I ordered up a bunch last summer, but he now carries them as a standard product. Its $90, but the shipping will get you back to around $105.
Anyways, here is the link. Careful to understand his two options: "One Vent" means one vent in front, which is the normal Carbon Cub configuration. Total two vents; one front, and back.
His "Two vents" are for planes like the one I had, where I ordered two extra vents, so two in front and two in back.
Important that you order the right one.
Here is the link for the ONE hole in front (two total):
http://aero-shields.com/catalog/i189.html
Rick