729 Friendship Battle Taichi Table Tennis Rubber is changing tradition and innovating the future.  729 Battle Taichi is a new tacky rubber. The sponge come with this rubber is the innovative two-color and duel-density sponge. It is called progressive structure sponge.This combination have enabled table tennis enthusiasts to have a deeper and broader imagination about the sports.the duel-density sponge hardness is 37-39 which means the sponge layer close to the top sheet is 37degree and the sponge layer close to the blade is 39 degree.