I'm assuming that the 12's will be the same, but I emailed them about the 18's suggested specs, and the sketchup/cut sheet not being the same. He sent me a link to the ZV4 info, which if you look at the address as the "X" in it as well now.
http://www.sundownaudio.com/misc/Boxes/X-Zv.4/Sundown%201-X-Z-12.skp