DONIC Bluestorm Z2: A POWERFUL STORM Z2 has a long, thin pimple structure and a large pored sponge. This 47.5° medium hard sponge is ideal for many players. One feels the storm and its power with the first contact and can direct use this energy where one wants. Great speed, enormous rebound, with excellent spin and speed characteristics. A concentrated demolition charge! DONIC BLUESTORM - A storm brews ! BLUE ALERT A comprehensively thinner top surface rubber, subjected to high tension, allows space for a thicker sponge - generating extra power and speed. The DONIC Bluestorm Series offers noticeably greater acceleration whilst retaining its outstanding spin and speed characteristics, making the latest trend.