Yonex VCore SI 100 : With the Yonex VCore SI 100 tennis racquet, you'll experience a frame that bites back thanks to enhanced grommet technology and string hole design that allows for more main and cross string movement, resulting in longer dwell time, extra bite and exceptional spin performance. This sensor-ready racquet allows you to attach the Smart Tennis Sensor and visualize your play. Sony Sensor-compatible with the SO1 adapter ring. Endorsed by Juan Monaco. Isometric™ increases the sweet spot by 7%. Super Cushion Grip minimizes vibration. Black Micro Core provides increased face stability. 3D Vector Shaft generates supreme face stability. Comes with a Yonex vibration dampener.