I gather it's also available for the F5. It seems to trying to do what the Arri Amira offers for balancing the camera when shooting hand held.

Sony F55 ENG & Doc Dock | Film and Digital Times (http://www.fdtimes.com/2014/04/07/sony-f55-eng-doc-dock/)

Meh. When it was initially announced, I was excited. The longer I go with my F5, the more I get used to it and now I'm pretty comfortable. I've since decided to take just about the same money and got an FS7 - something that I can bill for and will make money.