Yonex Smash Heat Blue

he ISOMETRIC™ equalizes the length of the main and cross strings in the string-bed, enlarging the sweet spot for more consistent accuracy even on off-centre hits.
 
Created by YONEX in 1980, the ISOMETRIC head shape is a unique and evolutionary breakthrough technology in racquet design. In conventional racquets, the sweet spot is located where main strings and cross strings meet. The YONEX ISOMETRIC head shape allows us to increase the number of main and cross strings that meet in the centre of the racquet to produce a sweet spot which gives a 7% more effective hitting area for you to make match winning shots.