Dunlop Sonic Core Ultimate 132 Squash Racket (2020) The Dunlop Sonic Core Ultimate 132 squash racket offers great control and power from a conventional head shape with a larger head size, making it perfect for players looking for more forgiveness without compromising power. Powered by Srixon. The new Dunlop Sonic Core range is made with Infinergy by BASF which is a super elastic material which increases rebound height by up to 46%, when combined with the Sonic Core frame results in a faster ball speed off the racket. Pocketed grommets and an aerodynamic cross section increase racket head speed for better manoeuvrability. The new GlidePolymer reduces friction and increase string movement for enhanced power and increased durability.