I asked that question couple weeks ago. No response.
I've been asking around, got some answers from desertheat who posts on here. He's a close buddy to the engineer (?) of OZ.
If I remember correctly, there's basically zero difference other than the cosmetics of the crossovers they sell today. The crossovers they sold couple years ago was a little square black box, and the ones they sell today looks a little like a lightning bolt where the letter "Z" is.
