Butterfly Tenergy 05 is the first family member with a special feature containing in the original shape of the pimples. High Performance for a Topspin Attacking Strategy “Spring Sponge” is the latest innovation from Butterfly. It is the sponge of the coming era. The well-known High Tension technology of Butterfly is now combined with “Spring Sponge” to produce a new rubber family. The product carries our development code No. 05 and merges High Tension technology with the characteristics of a highly grippy rubber.