Didja search?
Here's an earlier KS post about it:
http://www.brianmanzella.com/forum/golfing-discussions/12540-early-extension-2.html#post148917
A post with some info:
http://www.brianmanzella.com/forum/golfing-discussions/12373-my-lesson-brian-3.html#post148099
Brian's description
http://www.brianmanzella.com/forum/...ubface-control-very-elusive-4.html#post142024
Maybe you didn't need that info, but it might help others (or me) who look for it.