Butterfly Tenergy 64-FX comes with High Tension technology that provides a fast dynamic rubber to be produced by utilizing the innovative SPRING SPONGE. SPRING SPONGE enables a player to "grip" the ball and "catapult" the return back at high speed and with heavy spin. Tenergy 64-FX has all of the advantages of the Tenergy 64 top sheet combined with the softer version of Spring Sponge. Produces maximum speed, whilst maintaining control.