You can find in depth product info here:
http://www.babolat-purestrike.com/en
In short, we made the beam wider at 3,9, 12 o'clock and in the throat to give the racket improved stability. The string pattern has been updated with FSI Power, meaning the crosses are now wider for improved power. X - sider technology has been removed from the racket.
The 18x20 is (unstrung) 305 grams, 320 mm balance, and 98 sq in.