With the introduction of Black Zone, Tourna delivers a German-engineered co-poly that blends a very stiff base material (called PETP) with some carefully chosen additives designed to increase elasticity, comfort and feel. For our team, this recipe not only translated into exceptional control on full swings, but it also managed to keep Black Zone from feeling dead or too stiff on slower strokes and off-center contact. In other words, we think Tourna got the feel just right. Another noteworthy feature was the spin potential. This string's combination of bite, control and pocketing made it extremely easy for us to control the ball with spin. This co-poly is probably too firm for the player who needs the comfort and power of a pillowy multifilament, but for big hitters with solid mechanics, Black Zone offers a combination of control, durability and spin that is hard to argue with, especially when you consider the price.