[Cube] Sonnet "Cube kit"

[Riba]

I decided to go ahead and finally buy a CPU upgrade.

I want to get the Sonnet 1.2 GHz upgrade but it seems they are hard  
to find with a decent price. Provantage has the 'non-cube' version  
available for $211:
http://www.provantage.com/sonnet-sg4-1200-2m~7SONT02T.htm

Am I right that the only difference between cube version and this one  
is the inclusion of the "cube kit"?

What does this cube kit contain? I know there was a fan included, but  
I already have fan inside. Was there a special heatsink adapter?

Thanks!