$46/dozenGold4 stars5 stars4 stars2 starsContinued from last year, the cores are constructed of an injection-molded polymer resin instead of traditional rubber. The purpose is to improve the power of the core and stretch the ratio better between low spin off the driver and high spin off the wedge. How? By increasing the ball s moment of inertia with denser outer layers versus less dense inner layers.Use of the X and S is split among Nike's tour staff, a sign that each has few compromises. We also like the green aspects of this ball chemistry.