Babolat RPM Blast tennis string is the new string used by Rafael Nadal and Adny Roddick. An excellent choice for big hitters looking for extra spin. Octagonal (8-sided) cross-section adds the extra bite on the ball for added topspin and slice. New high density co-polymer polyester (PET) monofilament combined with a new cross-linked silicone coating provides even more spin and greater ball control. Babolat Tennis String 241101-105-15L