Dunlop Srixon Sonic Core Technology

Sonic Core Technology
Sonic Core Technology utilizes urethane and silicone in the head of the frame to increase dwell time and energy return for power and spin.

Sonic Core with Infinergy
Starting with the 2019 CX Series and continuing through the 2020 SX & FX series and 2021 CX series Dunlop updates their Sonic Core Technology with a material called Infinergy. According to Dunlop, Infinergy is the world's first E-TPU (expanded thermoplastic polyurethene). Developed by BASF, this super elastic material is placed at 10 & 2 o'clock. It is desgiend to increase the racquet's rebound properties, resulting in higher ball speed. It also enhances dampening for a more comfortable feel at impact.