AE has two black plastic caps that work on the 17" Mojave; not sure about the 18" wheel.
For the 17" wheel: One is much "taller" than the other (i.e., sticks out further from the rim itself). And the newer one (the "shorter" of the two) has a more "agressive' shape and graphic sticker on it. I tried both, disliked them both, and decided to go with no center cap (painted rear "axle ends" so they look like the front ones in your picture). I trashed the center caps long ago so no pictures; sorry.