Well, there are two answers, really..
You probably hit with a thing called a V-Core 98, or maybe a V-Core 89T even
However, Tomic doesn't use them anymore after his fairly disastrous 2012.
Tomic has gone back to his Head radicals I think..
5.0 all courter. 2 x Donnay X-Dual Platinum 99s 2 x Donnay Formula 100s (no, really!)
"Tennis isn't easy" - Corners