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. Back with the Dunlop Bio F2.0 Tours fro the summer
"Tennis isn't easy" - Corners