The Sonic Xâ„¢ is Roto Grip's newest addition into the mid-priced market. It uses the all new Sonic "Boom" Coreâ„¢ with a new pearlized coverstock. This High RG core with low Differential gives you more length with an arcing breakpoint. The Sonic X gives you a smooth transition from oil to dry allowing you to control the breakpoint. Sure Grip Pearlâ„¢ reactive surrounds this core creating a stiffer coverstock for those dry lane condition.