That by which a stone of the extraordinarily light special sponge kept inside the grip (core) shows the marvelous power at the time of a batted ball is a super core system. I have the excellent effect of the following 3 on a super core system and achieve the overwhelming batted ball sense which has no these effect formerly.

Light.
A racket becomes light because a wood is cored and a hollow is made, and I'm stuffing there with an extraordinarily light special sponge. When a racket becomes light, swing becomes speedy.
I'd like a batted ball sense.
The hollow made inside the grip raises a batted ball sense.
It doesn't affect a hand.
For a stone of a special sponge (core) to absorb vibration noise at the time of a batted ball, a clear batted ball sense is achieved.