Players who can move the arm fast and strongly can execute a powerful
stroke with more spin if they use the harder Spring Sponge.
The ball digs into the rubber at impact, thus generating more power.
The more the ball digs into the rubber, the more speed and spin can be
imparted; the result is a powerful stroke. Spring Sponge makes it easier
for the ball to dig into the rubber, providing the power to regain
the original shape is thus strong.
With the harder Spring Sponge, the power is even stronger. In general,
it is difficult to let the ball dig in to the harder sponge and produce the
performance required. Using Spring Sponge it is comparably easy,
even with the harder surface. For the players whose arm swing is fast
and powerful, Spring Sponge excels.