Here's something about it on youtube:

http://nl.youtube.com/watch?v=y4XJx1PoivQ

(can take a minute to load)

Ow and Nighthiker: I've asked about the pressure cups. There the same size in both the 4'' and 6''.
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''It's time for Plan B...'' ''We have a Plan B?'' ''No, but it's time for one.'' -Stargate SG-1