The Babolat RPM Blast 18 is the string of choice for Rafael Nadal, and Jo-Wilfreid Tsonga. RPM Blast stays with the octagonal profile but enhances the spin generation through the use of a new dye and coating. The cross-linked silicone coating is designed to allow the strings to slide across each other easier. This serves two purposes, the first is that the string can move easily, effectively allowing the stringbed to play as a more open pattern. The second, of course, is to enhance durability by lessening string to string friction. Babolat's RPM Blast is a popular choice among strong baseliners seeking durability and spin to dictate the action. Construction: Extruded co-polyester monofilament Color: Black Gauge: 18 g /1.20 mm Length: 40 ft     Features: -Silicon based coating for snap-back -Softer Octagonal profile for Spin -Used on ATP and WTA Tour