Focussing controllers

[Mystery57]

Was browsing the net when I came across the following gizmo

http://www.aputure.com/blog/2012/08/15/introducing-v-control-usb-follow-focus/


Has anyone any experience of using one of these - curious to find out more about potential benefits of controlling the camera off camera so to speak

 

[Flightphoto]

Handy for video and Macro shots by the look of it! Never seen such before though!

 

[Mystery57]

I thought similar with regard macro shots and stacking, hence posting for feedback